Been having trouble getting the boat on plane. Once on plane, it runs/drives great. Speed/RPM are just where they should be. But, again, the trouble is getting on plane in the first place.
On a lake, with light load, not much problem. But, with a heavy load, problems. On the river this last weekend (light load), struggled to get there.
I know that everyone here is going to scream "TRIM TABS". Unfortunately, those just aren't in my future. The cost is more than I've got available. Also means that I'd have to relocate my transducer and the stick-on mount pad that it's screwed to (I've heard that those are not too fun to try and remove).
So, I've committed the cardinal sin....I put a new hydrofoil on my motor.
Before you nail me to the cross...I did not re-use the one that I had for my old motor. It was an older design that you had to drill/bolt to the cavitation plate. This one is an SESport 400. It can be mounted with or without drilling. I opted for the no-drill mount option so my new (at least still-new-in-my-eyes) motor still hasn't been "violated" with a drill.
I'll update when I get a chance to take it for a test run. Here's the pics:
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It has absolutely nothing to do with the topic. But, if you do crucify me, this poor spoiled-rotten pooch is going to be quite sad. Nobody wants that, do they?
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Ok folks... you hold him down and nail him up (clearly well deserved)... I'll grab the lab and run away...
absolutely the way to go. Old 2 banger 2 stroke 50hp and mine jumps right up w/the whale tail.
Out of curiosity what is "heavily loaded" and "lightly loaded" and how trimmed down is your motor itself when you're trying this? You should really be able to get on plane pretty easily (especially on a river with a light load) without trim tabs unless you're dramatically underpowered which I personally don't feel you are. You technically could use them to get on plane (people sometimes do) and I'm sure it could help but the primary reason I'd never buy an Arima without them is because the ride is awful in chop without trimming down.
Sea hunter with a 60 should be no issue popping up on plane. No tabs needed. 4 blade prop also gives stern lift. How much does your boat weigh? Do you slowly ramp up or do you go to decent throttle in a short time. I used to slowly gas it but that always leads to the boat dogging for a while and now I just gun it and she floats up like a cork
Quote from: Norcalfish80 on June 26, 2023, 09:57:15 PMOut of curiosity what is "heavily loaded" and "lightly loaded" and how trimmed down is your motor itself when you're trying this? You should really be able to get on plane pretty easily (especially on a river with a light load) without trim tabs unless you're dramatically underpowered which I personally don't feel you are. You technically could use them to get on plane (people sometimes do) and I'm sure it could help but the primary reason I'd never buy an Arima without them is because the ride is awful in chop without trimming down.
"lightly loaded" would be just wife and I with light fishing tackle (usually trout), 3/4 to full tank of gas. "Heavily loaded" was full gas and a boat full of camping gear for a couple nights on the shore of Baker Lake (really struggled with that one). Going to be loaded a bit on the heavy side this upcoming weekend when I hit the bay for crab. I'll likely head out Deception Pass and try my luck in MA6 after dropping the pots.
When trying to get up on plane, I'm trimmed all the way down. When I do finally get it to plane, I can then trim up a bit to bring the bow up a little as that seems to be a smoother ride.
I'll note that my old motor had a whale-tail-style hydrofoil on it (was there when I got it). I really had a lot of control with the motor trim. It was almost like "flying" the boat. My new motor has never had quite that kind of control.
You need to do whatever works to solve a problem. If you can't do tabs, then the fin is about the only option, short of increasing power or always limiting the load in the boat. Unfortunately, lift and drag go hand-in-hand....creating lift always increases drag. The advantage to tabs is that you can raise them and eliminate the drag whenever you want to. The drag of the fin generating lift, plus the additional drag of all the mounting hardware, is always there. Despite the claims of the fin manufacturers to the contrary, you'll likely see reductions in top speed and fuel efficiency at cruise. If it works, sure can't fault you for finding a solution......although dognapping could become an issue. :wink:
BTW - I have tabs but don't use them all that much, except to level the boat against a beam wind or to stay on plane at low speed. My solution for rough water is trim down and slow down, works every time. (Although my definition of 'rough' has changed since I did my SmoothMoves seat) If I need to leave in a hurry, trim all the way down then hit full throttle and the 'up' trim rocker at the same time - by the time the boat's on plane, the trim will be just about right to pull the throttle back for cruise..
Quote from: christianbrat on June 26, 2023, 10:08:26 PMSea hunter with a 60 should be no issue popping up on plane. No tabs needed. 4 blade prop also gives stern lift. How much does your boat weigh? Do you slowly ramp up or do you go to decent throttle in a short time. I used to slowly gas it but that always leads to the boat dogging for a while and now I just gun it and she floats up like a cork
Not quite sure of the weight of just the boat. Varies depending on whether or not my fat @$$ is in it :rimshot: .
I used to go for the slow ramp-up. But, lately, I've tried to go to near full-throttle quicker. Neither seems to produce a good result.
Honestly my gut says there's something wrong with how your motor is mounted or your hull is waterlogged or something. You're sure you're propped right? That doesn't really sound that heavily loaded, especially since the weight of you and your wife would presumably be up front in the seats rather than on the back of the boat.
I echo the sentiment that you aren't propped well. Give us your set up data with rpm speed etc
Meister: It almost pains me to say it, but that bottom paint isn't doing you any favors when it comes to what you're experiencing. I'd bet if you could remove it, and polish that bottom, you'd see an improvement. My 16 SC, with a 60 HP Honda and highly polished bottom, was like a rocket ship.
I'd also put a big plus on Norcal's post relating to how the motor is mounted, propped, as well as the possibility of the hull itself being somewhat saturated. Just a suggestion, but maybe you could get it on a scale and let us know what it weighs. Before doing so, I'd also suggest removing everything from the boat that isn't tied down. According to the old brochures, the factory claimed a hull weight of 920 lbs. From what I've come to understand, that weight could vary a bit, from hull-to-hull. Obviously, your boat has some additional add-ons, but at least that should give you a baseline starting point.
Yat
I also use that same model tail for my '87 SR17, 2000 yami 115, 2015 tohatsu 9.8 and been sufficiently happy with performance. When I had this motor installed 2 summers ago it came without one and definitely took longer to get on plane. It felt loosey-goosey (had a lot of cavitation) when accelerating compared to responsiveness with the tail. I've also heard great reviews on trim tabs but haven't experienced personally. Are there major issues with using tails or are trim tabs just superior in performance?
I think you getting the fin is fine as long as it does what you want it to do. The other cost effective option would be to get Smart tabs, they are bit narrower I believe.
Also having a 4 blade is a great start, but make sure your prop is the right fit for your motor and your use, especially if your motor is not a command thrust.
Similar to Christian, I did the same when starting off, but I found for me, going slow at first to get the boat moving, then move the throttle faster to get to my desired speed was better.
They do the job, but are not ideal as they create drag and slow you down once up on plane. Top speed will be reduced. Fuel efficiency will be reduced as well.
fishmeister:
I see you're in Mt. Vernon. Hook up the boat and head out Hwy.20 Westbound towards Anacortes. Shortly before you get to the Sammamish Slough bridge, there's a little-used WA State weigh station on the right (North) side. The last time I looked, the scale was 'ON' all the time, just look through the window - big red LED numbers.
Pull forward until your tow rig back wheels are beyond the scale pad but the trailer jack is still above the pad, then read the scale for trailer axle weight. Unlatch the hitch and crank the jack down until the it supports all the tongue weight, then read the scale again for gross towed weight. Lower the jack, latch the hitch and drive away. (GTW minus axle weight = tongue weight, which should be at least 10% of GTW, preferably a bit more for stable towing) The trailer weight will be listed on your title - it's approximate, and won't include any options like spare tire and side bunks, but if you add those in and subtract the total from GTW, you'll be pretty close to your Arima's actual weight.
EZ and free, and accurate. (This is also a good deal for anyone heading to the San Juans, launching from Swinomish Slough, LaConner, Anacortes, Skyline or Cornet Bay)
Ok, had to dig through some of my old threads to find my prop data. Here it is:
After I got my new motor, I tried out the prop that I already had from my old one. After break-in, it turned out that I was still over-propped. At WOT, I was getting 5200 RPM. That's short of the recommended range (5500-6000). That prop was a Solas 4-blade, 10.8" dia X 12" pitch. Solas Part #: 1313-108-12
I bought a new prop. I increased diameter and lowered pitch. I hit the "sweet spot" perfectly. I'm now hitting 5750 RPM at WOT. That's right in the middle of the recommended range. New prop is also a Solas 4-blade. 11.1" dia X 11" pitch. Solas Part #: 1313-111-11
I did end up loosing about 1.2 mph off of the top-end with the prop change. I was getting 29.9 mph out of the 12-pitch and I'm now getting 28.7 mph out of the 11-pitch. I rarely cruise at that speed so I'm not really worried about that.
Just some details about my "back of the boat" set-up at testing time....
- Had a nearly-full 12-gallon main tank.
- Had a full 3-gallon tank (for kicker) on the port side.
- Have a Merc 9.9 kicker on the port side.
- Have dual batteries in the stern, on the starboard side.
If the hydrofoil costs me 1.5mph or less on top-end speed, I can live with that since I rarely try to drive that fast anyhow (I prefer to take it easy and save some gas most of the time.). As for overall fuel efficiency, time will tell. My gauge does track that in live-time. So, I should be able to see if there is a significant drop. If I'm "optimized" (as my gauge calls it), I was getting about 6.7 to 7 mpg without the hydrofoil (once I made it onto plane).
Quote from: davidsea on June 27, 2023, 07:05:47 PMfishmeister:
I see you're in Mt. Vernon. Hook up the boat and head out Hwy.20 Westbound towards Anacortes. Shortly before you get to the Sammamish Slough bridge, there's a little-used WA State weigh station on the right (North) side. The last time I looked, the scale was 'ON' all the time, just look through the window - big red LED numbers.
Pull forward until your tow rig back wheels are beyond the scale pad but the trailer jack is still above the pad, then read the scale for trailer axle weight. Unlatch the hitch and crank the jack down until the it supports all the tongue weight, then read the scale again for gross towed weight. Lower the jack, latch the hitch and drive away. (GTW minus axle weight = tongue weight, which should be at least 10% of GTW, preferably a bit more for stable towing) The trailer weight will be listed on your title - it's approximate, and won't include any options like spare tire and side bunks, but if you add those in and subtract the total from GTW, you'll be pretty close to your Arima's actual weight.
EZ and free, and accurate. (This is also a good deal for anyone heading to the San Juans, launching from Swinomish Slough, LaConner, Anacortes, Skyline or Cornet Bay)
Ironically, I was just across that same scale with my truck a couple weeks ago. I have a new-to-me travel trailer. I'm going to take it across the scale to check the loaded weight. I wanted a baseline of just the truck for whenever I get around to doing that. I can use that same baseline to weigh the boat. I'll likely do that this upcoming weekend. I'm planning to head out to Cornet Bay, drop some pots, and probably try my luck trolling along West Beach (MA6 opens the 1st).
Quote from: Yachter Yat on June 27, 2023, 07:26:41 AMMeister: It almost pains me to say it, but that bottom paint isn't doing you any favors when it comes to what you're experiencing. I'd bet if you could remove it, and polish that bottom, you'd see an improvement. My 16 SC, with a 60 HP Honda and highly polished bottom, was like a rocket ship.
I'd also put a big plus on Norcal's post relating to how the motor is mounted, propped, as well as the possibility of the hull itself being somewhat saturated. Just a suggestion, but maybe you could get it on a scale and let us know what it weighs. Before doing so, I'd also suggest removing everything from the boat that isn't tied down. According to the old brochures, the factory claimed a hull weight of 920 lbs. From what I've come to understand, that weight could vary a bit, from hull-to-hull. Obviously, your boat has some additional add-ons, but at least that should give you a baseline starting point.
Yat
Honestly, I have no need for the bottom paint as the boat lives on a trailer in my driveway. But, it was on the boat when I bought it and I've had no ambition (yet) to remove it. But, I do agree that it would look nicer without it.
Quote from: fishmeister on June 27, 2023, 07:52:44 PMHonestly, I have no need for the bottom paint as the boat lives on a trailer in my driveway. But, it was on the boat when I bought it and I've had no ambition (yet) to remove it. But, I do agree that it would look nicer without it.
That's me too, it would look nice without it, but no ambition to remove it, yet. :jester: :beerchug:
I don't think my boat is a good comparison but are others running 11" pitch props? I realize a lot depends on diameter and design but aren't most running 15", 17", or 19" pitches?
Quote from: AJFishin on June 27, 2023, 08:48:08 PMQuote from: fishmeister on June 27, 2023, 07:52:44 PMHonestly, I have no need for the bottom paint as the boat lives on a trailer in my driveway. But, it was on the boat when I bought it and I've had no ambition (yet) to remove it. But, I do agree that it would look nicer without it.
That's me too, it would look nice without it, but no ambition to remove it, yet. :jester: :beerchug:
It could be ugly under the paint. Sometimes boatyards really rough it up with aggressive grit Sandpaper before applying the bottom paint.
Quote from: croaker stroker on July 02, 2023, 10:23:08 AMQuote from: AJFishin on June 27, 2023, 08:48:08 PMQuote from: fishmeister on June 27, 2023, 07:52:44 PMHonestly, I have no need for the bottom paint as the boat lives on a trailer in my driveway. But, it was on the boat when I bought it and I've had no ambition (yet) to remove it. But, I do agree that it would look nicer without it.
That's me too, it would look nice without it, but no ambition to remove it, yet. :jester: :beerchug:
It could be ugly under the paint. Sometimes boatyards really rough it up with aggressive grit Sandpaper before applying the bottom paint.
I'm not sure how it looks on the hull, but on the transom the gelcoat was smooth, well until I removed it in a couple spots. :doh: :jester:
Quote from: AP on July 02, 2023, 10:15:40 AMI don't think my boat is a good comparison but are others running 11" pitch props? I realize a lot depends on diameter and design but aren't most running 15", 17", or 19" pitches?
Arimaownwers are running propellers from 10" to 16" diameter and pitches from about 10" to 23", depending on what boat/motor combination they have and how heavily their boats are loaded. Ideally, the best propeller for each boat will provide good acceleration, low planing speed, an economical cruise speed, and allow the motor to reach the top of the rated RPM range when lightly loaded.
Without any info about what you're running and how well it works....can't even guess.
I think you're all over-thinking this. I have an '89 Hunter with a 75hp two-stroke Merc and an 8-hp four-stroke Yamaha. This makes the Hunter a bit back heavy. So I put three 7-gallon containers full of water in the front cuddy and the boat pops up on plane so fast that it sometimes amazes me. WOT with two big guys, gear, fuel, etc occasionally tops 30mph depending on conditions. Easy,fast, and cheap fix...
When I bought my boat, it had a 50hp Merc 4St. It had a Solas 4-blade 10.5" x 14" pitch. It was severely over-propped. It literally shuddered when trying to plane. When I was able to plane, 4200 rpm @ WOT was the best I could do. That was WAY out of the recommended 5500-6000rpm range. I dropped to a 10.8" x 12" pitch and got a lot closer (about 5200rpm). That was the same prop that I started out with when I got my 60hp last year. It still turned out to be a wee-bit over-propped. My current prop puts me right in the middle of the range at 5750rpm/WOT.
I've been out a few times with the foil on. Been a bit hard to get some conclusive data due to water conditions. But, I have been able to note a few things:
- I definitely plane easier with the foil. Today, I was still able to plane the boat with the added weight of crab pots and a couple buckets full of water/crabs sitting in the stern.
- I have better trim control using the motor trim. It's much easier to control my bow up/down.
- I do think I've sacrificed some top speed. Again, how much loss has been hard to gauge due to the water conditions that I've been in. In a couple of weeks, I hope to be back on Baker Lake. If the water is calm, I'll be able to open it up and see just where I'm at for top speed.
As to overall fuel economy, the jury is still out on that.
Meister: Just looked at stickball's Hunter pics and noticed he's running a 3 blade prop. Curios as to whether or not you've tried a 3 blader?? I've never had occasion to run a 4 blade on any of my boats as I was always under the impression the benefit provided by that extra blade was somewhat offset by the inherent 'drag' due to the added blade area . :shrug9:
Notwithstanding props, I still say that bottom paint.....along with the kicker, two batteries and any other weight you carry, is bound to levy a fairly substantial tax on your performance; especially with respect to time-to-plane. Needless to say, it would certainly be interesting to see the difference with that bottom polished, one battery and the kicker left in the garage. I love that Hunter, but (like my 16 SC) I came to learn, even a seemingly minor amount of additional weight on the backside of these small hulls can make a huge difference.
In any event, have fun and please keep us posted.
Yat
When I bought the boat, I got a box of "stuff" with it (most of it turned out to be useless). There was on old, beat-up three-blade prop in there. I never ran it. As noted, the boat had a new 4-blade on it (albeit over-propped). So, to answer the question, I've never tried a three-blade prop. I'll admit that I don't have anything to truly compare against. But, some of my travels include my local river and Diablo Lake. The river has channels that are constantly changing. Diablo Lake (man-made, for those unfamiliar) has a long and relatively narrow canyon at the head of it. This is where I fish that lake. In both cases, good "bite" and turning response are important. I've read that a four-blade is better for this so I chose to stick with that.
The boat already had the dual batteries when I bought it. I like the added "comfort" of having a second battery available, if needed. I'm not willing to ditch a battery. I also use my cuddy space (what there is) for gear storage. and don't have room to move a battery there. So, I'm afraid that the batteries (both of them) are staying put.
I prefer to troll when fishing. Most of the time, I'll run the kicker for this. It's much cheaper on gas and saves hours on my main. Also a factor is that some of my fishing (trout and sockeye salmon) is best at a really slow speed. I'll admit that my 9.9hp kicker is probably a bit more than I need with a SH. I'd probably do just fine with an 8hp. But, money is an object for me. When I bought the kicker, I also wanted a motor that I could remove and drop onto my 12' Lund, if needed. I also like knowing that my kicker has enough oomph to push my Arima home, even against the river current, if needed (has happened with my old main motor). So, the kicker also stays put.
You are correct that this does add a substantial weight to the butt-end of the boat. Getting up on plane with that weight is the problem that I'm trying to solve here.
I wholeheartedly, 100%, agree that the boat would look much better without the bottom paint. I also imagine that it might help a little on the performance to have it waxed/polished. I certainly would not have put it on as it's totally unnecessary for what I do with the boat and how I store it. But, I just don't have the ambition, or money, to have it removed right now. Maybe later.
Well.....I don't know. I hear you, but judging by what you posted, I can think of only two helpful alternatives that might help: As painful as it might be, the first is (obviously) to get that bottom clean. The second, (which might be considered 'minimal') would be to swap the two group 24 batteries in favor of a single group 27 deep cycle. Following that, I suppose carrying as much weight forward as possible would be the only other option.
Yat
Had the boat out yesterday for crab (MA8-1). Actually had some really nice water and was able to open up to WOT for enough time to get some decent info.
I was able to to get 28.5mph/5750rpm @ WOT. That's only a loss of .2mph from prior to foil installation. One clarification is that, although not really strong at the time (right near slack tide), I might have had a little "help" from the tide.
For a true test, I'll have to get onto a lake (no current). But, the top speed loss that I thought I had may not be nearly as bad as I originally thought. If I've lost 1mph or less, I'll consider that a success as I rarely have the need/desire to run that fast anyway (I prefer to cruise a little slower to save gas).
As already noted, the foil definitely helps with planing and trim control.
I'll update this as I get more info.
Just for reference... yesterday I got out on the river for exercise, not glassy, but wasnt ocean either... 31.6 mph at 5800 max rpm; fuel flow was sucky: 9.2 gal/hr; but I never travel usually WOT... 15-20mph is rippen' in the ocean (I need to to clock my actuals in the ocean someday). Main motor mounted with a permatrim (which does help, and takes a little extra fuel, but not bad if looking at my spreadsheet), and trim tabs set at 2, main motor trimmed up just a little, with a slight tail wind (2 mph). My boat I know is heavy, 3350 lbs with the trailer. Fuel tank (23 gal) was 3/4 full, just 1 person solo, but lots of stuff in cuddy, big seats/suspension, auto pilot, alum wheelhouse, 2 batteries, kicker, etc... not to mention, I usually carry about 400+ lbs more in crab pots/puller or salmon gear, ice, tackle, snacks, wife, etc.
1985 17' SC with a 90 Yamaha 4 stroke. 4 blade alum prop (see chart for size)
(ps. pic of stern is old, since then, swapped out/upgraded ez-steer mount on main, and turned the kicker attachment upside down)
Baba, I would say that your top speed is pretty good considering your pushing A LOT of air with your pilot house. I've noticed on my previous soft top boats that if the soft top is up my MPH takes a hit compared to having it down.
15'11" with a 90 and PH.. can squeeze another 1 or 2 out of it.
Wow, didn't know a 90 could do 40 @ 8.3 ; that is really good; with a hard top to boot; is your 16'r got less weight? shows what my boat is capable ?
I'm still not convinced I could maybe dial my prop just a bit betters, but i don't don't know how? or not ? My 5800 max @ 9.2 gpm just shows generally how heavy I am; I don't necessarily think it's too ass heavy, but I don't know.
8.3 remaining, not my fuel flow. Not sure what my flow is at that speed but probably not that economical haha
Funny, but while you guys are talking about performance, I'm still trying to decide what species of wood Meister would most favor for his "Crucifixion". :facepalm: Since he's from the NW, do you suppose it should be something like quarter sawn Red Cedar? Hey......just asking. :shrug9:
:jester: Yat
that would smell pretty pleasant
Quote from: christianbrat on July 06, 2023, 08:39:49 AMthat would smell pretty pleasant
Yeah, right up until you hung me on it!! :jester:
Christian,
Red Ceder sounds good.
btw,
What size and brand, model prop do you have ? 4 blade? I didnt know that 16 has a 90.
baba.
Quote from: Baba on July 06, 2023, 09:10:49 PMChristian,
Red Ceder sounds good.
btw,
What size and brand, model prop do you have ? 4 blade? I didnt know that 16 has a 90.
baba.
I have a stainless Honda 3 blade 13.25×17. Totally awesome setup
Hmmm., maybe try a 17? Im gonna call Phil at Turning Point next week and ask what he thinks if I went from my Alum 4 blade 13.5x15 to Alum 4 blade 13.25x17 ?
Im stuck on the idea that the 4 blade is more stable in ocean, with my weight.
\ I like the idea of Aluminum gives me maybe a chance of not breaking my lower if I ever hit something... but wonder if its worth $125. to find out what my results are ? ... In fact, he may even let me test it and return it if no bueno.
It would be nice if my mid range gph goes up, ie run mid range at lower rpm... and I can still attain 5700-6000 WOT, Im still trying to wrap my head around what optimum WOT has real effect on mid range...I think that WOT is an important parameter to be at near max designed rpm, Ive heard that's key for good engine longevity to not lug the motor, even if running at WOT is very seldom.
Any thoughts?
Well, I think I'm going to put one more "update" to this thread as a "wrap-up" just in case anyone wants the info in the future....
I don't have any detailed spreadsheets to offer. I've been running the boat in a variety of water and load conditions.
I can say, definitively, that the hydrofoil has helped my trim control. I have a lot better control of the boats trim with the motor trim control than I had before installing the foil. Could I have gotten this with tabs? I'm sure I could.
When I was able to get onto open/smooth water, I only lost about .3mph off of my top-end. Since I rarely try to run that fast anyway, I'm fine with that.
Can I get the boat onto plane easier? Absolutely a "yes". In fact, last weekend, I was at Baker Lake for the Sockeye opener. I had the boat quite heavily loaded with camp gear and coolers of ice for two nights (and my wife is still struggling with the "pack light" concept). It took quite a bit of time to get the bow to come down. But, once I reached speed and the bow started to drop back down, I was able to pull back the throttle, trim up a bit, and cruise at 25mph without even needing to be at WOT. I didn't even have to shift every possible item to the front of the boat. I had a very nearly identical load for a trip on the same lake for Memorial Day prior to getting the foil. I wasn't even able to plane the boat at all. So, I'll call this a definite improvement.
Does the foil cut into my fuel economy? I'm still not certain as to what, if any, impact the hydrofoil has had on overall fuel usage. I do think my overall MPG might have dropped a little (.5mpg or less). But, when I'm unable to plane (or struggle to get there), my MPG is definitely much worse. So, while I may have taken a slight "hit" on economy while on plane, I'm hoping that being able to plane quicker/easier may offset that enough to be close to a "wash".
Overall, I'm satisfied with my SESport 400. It has done what I wanted it for, and at a more economical price than trim tabs. Installation was quite easy. I used the "no-drill" mount option so I still have a cavitation plate that hasn't been "violated". Two things that I'll note for anyone else who opts for this....(1) The mfgr advises not to over-tighten the bolts when installing or they can snap. Please trust me that this is correct info :doh: . If you snap the bolt, you may have to go searching for a replacement. A SS 1/4-20 x 1.25" carriage bolt was harder to find than I expected. Ended up at Tacoma Screw for one (really nice guy actually gave me the bolt). (2) There are some online reviews that mention them just "falling off". One thing the mfgr recommends is that you should re-tighten the nuts after a use or two. This is also good advice. I was able to tighten the nuts about a quarter turn after the first use. Mine seems to be rock-solid now. I expect that some of these reviews are from folks who didn't follow this recommendation.
I know that trim tabs are revered/sacred here. In fact, I initially hesitated in starting this thread (hence the title). I'm sure that tabs have their place and probably do have some advantages over a hydrofoil. For those who have them and like them, that's great. But, after starting this thread, I found myself a little surprised when some others chimed in and said that they were also running "whale tails".
Summary....If I had the budget and was willing to move my transducer, I probably would have gone with tabs. But, since that was not reality, I went with the foil. I don't regret my choice. While not necessarily the "perfect solution", it's good enough for me.
I have smart tabs on my 17 s.c. and I love them. Power is a 2010 Tohatsu 90 TLDI. And I usually run pretty heavily loaded., But, on my previous boat, a sea hunter I was running an older 50 Johnson, twin cylinder, with a whale tail. Worked fine, but had to learn to control my motor trim.
Twenty years ago I repowered with a Yamaha 50 HP and the first thing I did was put a Foil on the motor to help get up on plane. By myself the boat literally jumps up on plane. Yes, I too have learned to use the trim control to even out the boat, 25mph @ 4500 rpm. Zero regrets on economy...... its a Sea Hunter!
I've never had a hydrofoil on any of my boats so can't really speak with any authority on the subject. The only education I ever get on these is from guys (such as yourselves) who've actually used them, or from articles I've read. In consideration of that, I seem to recall comments to the effect that if the motor was mounted too low, then the foil (being too submerged) could create an excessive amount of 'drag' that could serve to offset some of the potential benefit. Leads me to wonder if raising the motor under this condition might be of some benefit.
Course, I suppose cavitation would be no fun either. Hey....with that in mind, does anybody know if there is any evidence that these foils (in some way) help prevent cavitation? :shrug9: Curios.
Yat
Cavitation... I don't think a fin would have anything to do with the pressure or lack of pressure on a propellers blade. Now ventilation it does influence (a physical barrier in the water), but only at up to displacement hull speed (anything faster and the turbulence generated is well behind the prop, not sucking air down a whirlpool).
Maybe?
JDB: Yeah, you're right! Thanks for the correction. I should have said 'ventilation'. I actually know the difference between the two, but sometimes use one to mistakenly describe the other.
So, that aside, why might we suppose these foils could help eliminate, or at least minimize, ventilation? Seems it might be something to research; especially for those considering this as an option.
BTW, here's a quick esplanation: https://www.youtube.com/watch?v=5bj5kjh3l9o&t=7s
Yat
Hmm maybe the fin is creating a pseudo tunnel that the water being flung off he edge of the prop has to go through, instead of just creating spray?
Such as the portion of the thrust cone close to the surface is forced rearward, instead of being able to create spray at the surface?
Or, just the physical barrier from the surface at speed, reducing the amount of air taken in by the descending blade? But that kind of doesn't make sense because there are propellers designed to be partially out of the water...
I didn't mean to correct anyone. The fin might change the hydrodynamic forces on a blade that actually reduce cavitation (but fluid dynamics are not really covered all that well in basic physics, and not at all in toxicology or criminology).
Notwithstanding humor, I simply have to say: If I had a foil on my outboard, I don't think I'd be all that excited about looking down at it (especially during my "normal" cruise speeds), only to discover it running completely submerged. :shrug9:
Yat
Hey......wouldn't it be something if somebody made a hydrofoil that attached to an outboard that would operate like the tail ailerons on an F22? Take a look:
https://www.youtube.com/watch?v=SrxzFUcBPuw
Would be especially nice if it was controlled by a small "joystick". :facepalm: (Nevermind, I know just what you perverts are thinking) :jester:
Okay,, I'm gonna brush my teeth now. :jester:
Yat
If I had trim tabs, this is the control I'd insist on. No "thinking" required. :jester:
https://bennetttrimtabs.com/product/joystick-helm-control-electric-only/
Yat