Would a foil help?

[2iar]

I've only got a 3.4m Clark Cutter, with a 9.9 Yamaha 2s.

When the conditions are flat, or I've got people up front, no real worries.

When there's just me and it's flat, I seem to take off with the bow high up before "levelling out" a bit (this is isn't really a drama).

When there's just me and even just a bit of chop, I spend a lot of time with the bow pretty high up, or banging up & down. It's pretty uncomfortable, hard work and difficult to steer.

I've got the motor trimmed out to the 2nd last slot. I obviously don't head out far either.

Would a hydrofoil help, and if so which one would be recommended? I'm happy to invest the dollars if it'll fix it (or help), but I don't want to look like a right w***er fitting one on such a small rig if there's no benefit...

Thanks for any advice,
Mike

[basserman]

mike they can getting on the plain in boat without enoght power as your case maybe but before going down that road i would first go for a run and test all the trim positons first
i would think you may need to trim the motor in to the middle hole or ever the second closest hole
however it would be up to you and knowing how the boat reacts to what
so test trim positions first and then if no better then look at a foil like LZ foils for under 50hp by Lalizas

[stunnedmullet]

Agree with basserman, Sounds like you may have trimmed your motor out a bit far. Try the second hole in.
The mullet

[2iar]

Thanks for the info guys.

I've got 4 trim positions. I used to have it at the second one in(2), now I've moved it to second out (3). Didn't seem to make much difference, but I'm not yet a great judge of conditions/tides/winds, and tried them on different trips.

I was thinking of giving it a good run over the same stretch of water in the same conditions with each of the positions, and I'll definitely give it a go now.

How much would I be looking at for the foil, and what's involved in fitting them? Are they supposed to be professionally fitted, or is it just a case of drilling a few holes and bolting it on?

Thanks again,
Mike

[Roo]

have you checked the motor height? The anti-cavitation plate should be approx 0-15mm below the keel. helps to reduce the drag. I've tried the LZ on my quinne explorer 3.5 with a yamaha 15. I found it popped out of the hole better but the trade of has been reduced top speed due to drag. I'm still experimenting with the motor height!!

cheers. :o

[basserman]

the LZ is proble the best foil for small motors up to about 40hp and they are pretty simple to fit on
they are a two peice foil so you will need to get them sitting pretty equal and once that is done just center punch the four bolt holes and drill out then bolt them on ;D
as said sometimes the trade off is reduced speed for the better hole shot and better cournering

[2iar]

Bear with me on this, it's all new to me...

I've heard of the cavitation plate, but ...er, um... what is it?

Is it that the bit above the prop that "shields" it? The horizontal bit that the foil presumably fits on to?

I've got a standard L/S (20 inch) apparently. Used to have a 6hp of the same shaft length which worked ok, but because of the lower speed, steering was fine and it didn't make the bow rise to the same height becuase of the lower power. Great little motor (I've still got it as backup), it just didn't go very fast.

That being the case, I'd imagine the height of the motor should be fine, but it's an interseting point and it's worth checking - I'll have a look.

Thanks for the advice so far...

Mike

[basserman]

yes mate you got it right the cavatation/aint ventalation plate it the bit right above the prop and that is what you bolt the foil onto makeing sure the prop woun't hit anything ;)

[2iar]

Thanks Basserman,

Just checked the Whitworths website, and they've got the LZ foil for a surprisingly low $19.90. Might be worth giving it a go regardless at that price (I thought they were much dearer). I'll just have to put up with looking a dill with a foil on 9.9 ;D

Sacrificing speed for getting on the plane properly and having more control is a fair trade off. I've GPS'd my top speed at 18 knots, which is quite fast enough for me in an 11 footer.

Thanks for your help mate, it's really appreciated.

Mike

[familyman]

Mike I would not yet be fitting a foil,try all your trim positions and if needed try changing the internal load ie tank and battery ,maybe move them forward slightly ,but first put your motor right in.If the boat feels hard to steer ,like it wants to follow a turn and not respond to the steering then the nose is too low,try one hole out on your trim setting.Just experiment before you drill for a foil.
good luck
cheers jon

[Dezzer]

If foils improve performance why aren't they fitted by manufacturers?

[Wyoming]

A mate of mine recently spent a lot of time developing a set of wheels that are fixed to a tinny so that you can tow it without a trailer. #As part of the "kit" he made some trim tabs that he calls "Tinnie-Tabs" and these are made from ABS and they are riveted to the transom.

What a difference these make! #You get the boat out of the hole almost instantly, even with a very small engine. #If you are interested, PM me and I will get your contact details to Jim.

Sorry about the quality of the attached photo, but it demonstrates the Tinnie-Tabs. In the photo, they are just fixed to the transome with heavy duty, double sided tape!

[Wyoming]

Whoops! Here is the picture of the Tinnie-Tabs

[DaveSue_Fishos_Two]

You have said that if you have people up the front of your boat then you have no real problems. Therein lies the answer to your question. ;)Weight distribution is everything, especially in smaller craft with smaller outboards. Put your fuel tank, battery if you use one, etc up towards the bow. If this is not enough weight, put in a bag of cement or something. I'm serious! Get more weight towards the bow and your weight at the back will balance your boat out. :D Out of the hole quicker and easier to handle.
Someone said on this post that the cavitation plate is there to protect the prop. Crap! >:(The cav plate is there to balance the water mass, flow etc around the prop thus aiding motor 'lift'. The bottom of the prop is what needs protecting and that is why your motor will have a 'fin' protuding from the gearcase.

Cheers and happy boating

Dave

[2iar]

Hi Dave,

I'd figured that weight up the front was the key, but there's nothing much to move up there - the fuel tank is at the back (I don't have a battery), but it's much more practical where it is...

My gut feeling is that adjusting the trim won't help much - I've tinkered with it a little bit before to no real effect. The bow doesn't go too high with someone up front, but the porpoising still occurs, but less pronounced.

That being the case, I think I'll throw on a $19 foil to see if it helps. It's a 15 yo motor, and not in the best knick paint-wise but runs well. Therefore I don't have a problem in drilling 4 holes and bolting one on. If it doesn't work, i'm not too much out of pocket, but if it does I've solved (or reduced) the problem at little cost & effort.

I don't really want to try the bag of cement option (though it would probably work) as I've just gone to the bother of pulling out the flotation under the front casting deck to store the anchor & PFD. Space is at a bit of a premium in an 11 footer, and a bulky bag's not that appealing.

It may have been my good self that used the term "shielding" the prop. I just didn't know how to describe if it was the cav plate I was talking about. I wasn't really thinking it protected the prop. I do know the bit at the bottom's called the skeg, so at least I'm learning, eh? ;D

Thanks for taking the time to offer the advice (that goes for everyone contributing to the thread). I've got no mates that are in to boating, and this site has been a god-send.

Thanks guys,
Mike

[2iar]

If foils improve performance why aren't they fitted by manufacturers?

Hi Dezzer,

My very inexperienced take on it would be that motors aren't designed with a particular boat size/mass/weight whatever in mind, but rather for a range of them, so sometimes they could be fitted to a vessel that is just a bit unsuitable to them. Rather than an expensive exercise of replacing the motor, they might be able to address *some* problems on *some* boats in *some* conditions. That is, they are an "option".

I've also read on Ausfish that they can even decrease performance/safety (in a following sea for example), so therefore you wouldn't want to be fitting them as standard.

Just an uneducated guess, mind you. How'd I go, experts? ;D

Good luck,
Mike

[2iar]

Anyone following this thread may like to know that I threw a foil on in about five minutes, and shot out on Friday and Saturday.

I have to say, it's the best $20 I've ever spent. Definitely a slightly lower top speed, but the comfort and steering have improved dramatically.

Almost certainly it won't help everyone, but if you've had the issues in a rig and conditions similar to mine, I'd thoroughly recommend it.

Only unforseen downside is that I had one of those collapsible flush bags for small outboards. Unfortunately the width of the foil on the motor means that I can't get the leg in the bag any more...no biggie, I'll just grab a pair of muffs instead.

Thanks for all the advice. I'm a happy man [smiley=2thumbsup.gif]

Good luck,
Mike