Hydrofoil help needed

[cos]

I have a 5.3m Haines prowler with a 115 Yammy 4 stroke. It's a little heavy in the arse end and when the sea is sloppy it can get bogged down under 15 knots.

I'm considering buying a hydrofoil. I was wondering if anyone else had gone down a similar path and if it improved performance.

[antonywardle]

I used to have a spare one lying around somewhere. If I can find it, you are welcome to grab it if you want to try. I don't use one myself. I figure that if they were any good then the manufacture would probably supply them. Some people will swear by them though.

 

[rickmarlin62]

What pitch propellor are you running

[Plethora]

I was having the same problem with my 115 E-Tek and was told (don't put one of those on you could tip the boat over) Bull S**T, This was one of the best things I have ever done - it now go heaps better at low speeds and jumps up out of the water to plane quicker - and saves on fuel

[JonD]

I have personally found hydrofoils to be quite dangerous in some sea conditions ( side on or rear quarter seas ) to the point they have forced me into immediate action turning with the wave to stop a roll over. In saying that, the sea conditions have been pretty severe, not when you really want to find adverse handling characteristics .

I've owned several Haines vessels and a little formula 15 which were all greatly improved by fitting simple self levelling tabs to the hull rather than the engine. Hole shot, lower planing speeds, economy etc etc are what the manufacturers claim and what I've found to be true on every vessel I've used them on. 

Another really good improvement I found to be worth while was changing to a 4 blade prop on a Haines signature 540 ( after advice from Solas props ). Unfortunately those 4 blades are quite costly though, where the self levelling tabs are relatively cheap.

The word is out there on extra pressure on outboard components after fitting hydrofoils and with some engine manufacturers warranties become void if you fit them, which tells you something.

There could also be other factors in play here, as many manufacturers fit eotboards low which helps in basic handling to novice boatiies. Those who understand trim better and want better performance will soon raise their engines higher on the transom for greater performance, which this picture bellow describes. Basic weight distribution can often be overlooked on small boats, especially when it comes to bogging down the stern. Bringing eskies and as much weight forward to balance the boat out will also help.

 

This video shows the kind of self leveling tabs I'm talking about. You will need to drill the hull, which some people are a little precious about but by using silicon in the screw holes you shouldn't have any dramas. 

 

 

 

[rickmarlin62]

Good advice jon  i still would like to know if he has too higher pitch to hold it on the plane at low speeds in poor conditions with weight in it......dropping from a 19 to a 17 can make a lot of difference         ps  i would steer clear of foils if u can

Edited December 5, 2019 by rickmarlin62

[antonywardle]

The TABS look interesting.  Anyone use them on a smaller (6m) plate boat ?

Do they interfer with the down/side scanning?

 

[cos]

Thanks for the feedback and sorry for the late reply (I've just finished a week of night shifts)

Antony thanks for the generous offer but if I go down the hydrofoil path I'll get ones designed for my  motor, thanks again.

I've been running smart tabs. Had a look at them yesterday and realised the shocks had broken. I've replaced them and going to go out tomorrow to give them a run. 1.5 m swell with 6 second period should give me some idea if it's improved.

Rick I have a 4 blade 17 solas prop so I think I'm on the right path there. I've only had a tiller steer tinny up to 3 years ago so still learning.

Plethora I've had a lot of people tell me exactly what you said...that's why I'm a bit confused.

John thanks for the video it gives me a better idea of how to use them properly, Quick question I think both of the boats you mentioned carry the v hull through to the back where mine flattens out. Does this make a difference to maintaining plane speed in slop?

[dunc333]

i put a se 300 on my yalta craft and she gets up on the plane alot quicker .being a heavy hull and can trim out more before cavition happens .i love mine ,and  Jon i see what seas you fish in lol . trim taps for sure as better option depends on your budget though

Edited December 9, 2019 by dunc333

[zmk1962]

On 12/5/2019 at 3:39 AM, cos said:

I'm considering buying a hydrofoil. I was wondering if anyone else had gone down a similar path and if it improved performance.

I'll just give you my own experiences. I purchased my big heavy, deep V Haines 635L back in 1996  - at that time it had a pod mounted Yamaha 225 XL with aluminium hydrofoil wings bolted to the cavitation plate, and across the stern there was one battery and a 10L oil reservoir.  

The previous owner used the boat for pulling skiers and tubes and overall I can confirm it popped up to plane pretty quick in a river or estuary scenario. I was new to offshore boating and never took it offshore in that configuration - so can't comment on any offshore behaviour or following sea issues with the foil.  But it was pretty evident there were cracks  on the cavitation plate ..... and so I took the foil off. There was negligible difference to hole shot in my opinion without the foil.

I then replaced the Yamaha with a Merc EFI XL, dropped HP down to a 200, added a 15HP aux, installed 3 batteries across the back and still retained the 10L oil reservoir. I also carry a 35L live bait tank on the marlin board. That's a LOT more weight across the back then when I was running with the 225.  Also I'm running the standard Vengeance  19P (14in) 3 blade S/S prop.   This is my Haine's performance with the 200HP:

2000-2100rpm 15-18km/h planing speed

3400rpm 40km/h, 

4000rpm, 55km/h, 

4200rpm, 58km/h,

4900rpm 75km/h

5800rpm ??? red line .... no comment

I have no hydrofoil fitted.

After the initial few sea trials, I had the motor raised until I could see the cavitation plate just below the surface at plane. I spent a fair bit of time on balance of the hull (100L water bladder up front under the port bunk, to offset the starboard mounted Aux and the bait tank), all the gear is shoved upfront and I also installed an anchor winch (about 50kg) right at the bow.  The below video should start at 4:18 which will show you hole shot (without gunning the motor). My wife was even standing at the stern so an extra 50kg or so there .... I do trim the motor in on take off (so the upward thrust helps lift the stern) and then level it out once the boat is underway.... not sure if that is visible in this video though.

In my view there is a lot be gained with correctly balancing your hull and playing with tilt/trim.

Personally given what I saw on the Yamaha I would not be drilling the cavitation plate. If a large cavitation plate was the answer you'd think the manufacturers would be releasing outboard with this feature standard just to get a competitive advantage.

Cheers Zoran

[garfield28]

I have one on my Merc Saltwater 125 that pushes a glass Savage 5.2m boat. When Scratchie come out with me he used to always say take that thing off as it seemed to make my boat cavitate haha when I would chat with him he'd say you take that silly thing off yet! So i did for a while, and I put it straight back on. I noticed that I couldn't get out of the hole as quick and on the plane, but also the fuel usage was very very noticeable! 

 

I personally like it as I have noticed first hand the difference it makes to my boat, but some very knowledgeable fisho's on this forum and would certainly take strong notice in what they say with their advice and would trust it over most. 

 

good luck, there's nothing worse than the boat struggling to get up and going.

[JonD]

16 hours ago, cos said:

Thanks for the feedback and sorry for the late reply (I've just finished a week of night shifts)

Antony thanks for the generous offer but if I go down the hydrofoil path I'll get ones designed for my  motor, thanks again.

I've been running smart tabs. Had a look at them yesterday and realised the shocks had broken. I've replaced them and going to go out tomorrow to give them a run. 1.5 m swell with 6 second period should give me some idea if it's improved.

Rick I have a 4 blade 17 solas prop so I think I'm on the right path there. I've only had a tiller steer tinny up to 3 years ago so still learning.

Plethora I've had a lot of people tell me exactly what you said...that's why I'm a bit confused.

John thanks for the video it gives me a better idea of how to use them properly, Quick question I think both of the boats you mentioned carry the v hull through to the back where mine flattens out. Does this make a difference to maintaining plane speed in slop?

 

 

The deep v hulls most definitely held the boat on the plane at lower speeds in rough conditions and level. The Haines signature had a lean to one side partly down to prop torque, so that side had the self levelling tab adjusted with an extra adjustment of pressure that kept the boat running true.

The issue I find from controllable trim tabs is once you correct for say heavy weather hitting you on one side, they are then in that position with no instant adjustment for different waves ( unlike the spring kind ). When you drop down the face of a swell and the wind no longer hits the side of the boat it suddenly gets a lean and by the time you get your hand back on the trim buttons the wind is back on your side again.

I drove a big formula over the weekend and though the electric trim tabs were helpful, there were also times in the rough stuff when they were totally annoying the hell out of me.  Trying to work the throttle in a quartering sea, steer and adjust trim tabs needed a third hand, driving formulas slowly is out of the question!!!😁

[Fishop]

If you already have trim tabs I doubt it would make much more difference.  I have a foil on a 90hp and a 5.6m boat.  Yea when I'm loaded right up I notice it helps to get out of the hole but with 2 or 3 on board it's negligible.  Top speed suffered by about 2 knots with the foil.  I leave it on because it makes a good step to get back into the boat with 

[JonD]

14 minutes ago, Fishop said:

If you already have trim tabs I doubt it would make much more difference.  I have a foil on a 90hp and a 5.6m boat.  Yea when I'm loaded right up I notice it helps to get out of the hole but with 2 or 3 on board it's negligible.  Top speed suffered by about 2 knots with the foil.  I leave it on because it makes a good step to get back into the boat with 

Gee a good step to get in and with, hope you are a feather weight!!!

Edited December 10, 2019 by JonD

[rickmarlin62]

Good way to snap off part of your leg  standing on a foil bolted on

[Fishop]

2 hours ago, rickmarlin62 said:

Good way to snap off part of your leg  standing on a foil bolted on

Im 85kgs.  My mechanic told me to stand on the foil and jump up and down to see if my gelcoat cracks are caused by transom flex.  I couldnt see any movement in the cracks.  Actually, he said get the biggest guy you know to jump up and down on your foil to see if the transom flexes.  Outboard leg should be strong as, think of the power of 90 horses pushing against it,  side on.  A puny 85kgs pushing down the length of the leg isnt going to bother it.  Its got one of those SE300 foils and its thick plastic barely flexes at all.

 

Besides, when you are getting into the boat from the water only a small portion of your weight is being supported by the hydrofoil.  my right arm is holding onto the top of the motor, my left arm is grabbing the transom well, and my left leg goes onto the transom.

[Fishop]

On 12/5/2019 at 2:39 AM, cos said:

I have a 5.3m Haines prowler with a 115 Yammy 4 stroke. It's a little heavy in the arse end and when the sea is sloppy it can get bogged down under 15 knots.

I'm considering buying a hydrofoil. I was wondering if anyone else had gone down a similar path and if it improved performance.

Forgot to mention, my boat was also a bit ass heavy.  I moved the batteries to midship from the stern so 40kgs from the rear to the front and that seemed to help also.