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Old 17 July 2015, 19:09   #1
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Hydrofoils worth the bother???

Well....seriously enjoying my new SR4. Haven't even managed a solo trip yet as my boys are glued to the rib!

Took them out for their first session on the donut\ringo\biscuit (everybody has their own term) and they had a blast.

But it just left me with a query....

My youngest despite being the daredevil in the family, is not just as confident in the water as his older brother.

He prefers being towed at a much slower pace.

Problem is, the slow speed means the nose is well up whilst towing him at the slower speed, even with his brother perched at the front doing lookout duty.

I was wondering if fitting these hydrofoils would help with getting the nose down a touch more at the slower speed? Not expecting miracles at such slow speed but getting the nose down a touch would be nice.

Now, if you think these would do the trick, could anybody recommend a quality product ...or warn of any to steer clear off? And do they have any negative effect on the ribs general handling?

There will be a fair bit of watertoy towing as the boys love it and the rib was boat as much for them as myself.

Just thought I'd ask outright on here as research throws up all sorts of opinions...and I would rather get some first hand, present day opinions.

I know there is the minefield of prop choice that could be discussed but tbh the standard Tohatsu prop No 11 seems a well matched all rounder.

I will say this...it pulls the toy with absolute ridiculous ease...in fact when it gets one the plane, I have to back off a fair bit immediately as it really ups its momentum significantly in a matter off a few secs. Despite me being told by a few people that 40hp would be adequate but not ideal for pulling the donut!

For reference, the engine is a Tohatsu M40C.
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Old 17 July 2015, 22:49   #2
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Theres a reason you lose your warranty on any engine over here with them fitted, they put extra pressure on engines steering bearings etc.

Ive owned fibre glass boats with them and while they do as advertised they can also exaggerate boats bad habits especially in rough conditions, where a boat can be hard to recover on big side on swells.

Ive found these self levelling trim tabs to be far more effective and much safer Self Leveling Tabs (SLT) | Bennett Marine

Jon
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Old 18 July 2015, 03:31   #3
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Used them for year on different boats, do what they say on the tin, plane a lower speed, encourage bow to drop etc.
Ive never had an issue with steering,or felt any il effects. My current boat has has them fitted and has done for 15 years, seems to still be functioning fine .

Years ago had a 4m dory, heavy old thing wouldnt plane with the 15hp we had lying around at all, until we put on the dolefins then it worked OK, slow but it planed.

They are like bovril, either you love them or hate them, and you wont convince either camp to change their mind.
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Old 18 July 2015, 05:50   #4
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After moving from the IOW to here (Aus) I soon found comparing the seas I used boats on over there are a little different from here. When I say they are dangerous in rough seas Im talking about large ground swells with big breaking waves, in these conditions most people wont be out in their boat but we do get caught out occasionally.

Has anyone asked any manufacturer if new engines are fully covered under warranty with them fitted over there, if not why not.

Have a search Pro's & Cons of hydrofoils on outboards you will find many people describing the effects I mention on non rib boats in rough seas. Ive owned boats that Ive happily had them on but only used those boats in mainly calm seas.

Self levelling trim tabs are simple and cost much the same, they also let you adjust each side of the boat differently to correct for prop torque or an uneven load (console and batteries on one side etc). Full electric (hydraulic) trim tabs become much more expensive and trickier to master.


Jon
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Old 18 July 2015, 06:51   #5
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Those trim tabs look interesting. The self adjusting ones with no electrics hydraulics etc.

Thanks for that...I will look into this a little more.

The rib planes very quickly on a whole. And many inc Tohatsu have advised that the standard prop really is the best match for the engine regards all round usage hence was looking at other avenues.
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Old 18 July 2015, 08:54   #6
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Having used small boats with them on in up tom btf 8/9 ive never noticed any untoward handling characteristics that were not down to using a small boat in silly seas.
Admittedly ive never done back to back tests (done out with dolefins on tested, then come back taken them off and tried again), but i cant say ive ever felt a bad sensation that i could attribute specifically to them.

Dole fins 25
Trim tabs 90

As to prop size, a one size fits all prop would seem to me to be a strange thing to say, will it work of course. Put the same engine on boats of different weights, styles/hull config you will get a different result. as long as the engine is running in optimal rpm range then most props will do. but will not be optimal.

You can play with this to see what you get Prop selector
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Old 18 July 2015, 09:45   #7
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Yeah, completely fair point.

Should have elaborated...have been advised that the standard prop suits the SR4 well for general all round pleasure usage.

Not having a lot of experience yet on the rib just thought I would avoid starting to mess with props just yet. Had just wondered about the fins as a simple aid.

The boat planes very very quickly. It's just my youngest is comfortable at what I consider a very slow speed and it would be good to just get that nose down a touch more without causing issues elsewhere.

I appreciate the feedback and welcome anyone's opinions as many on here seem plenty more knowledgeable than myself.

Seems like one of these options will work.

Just for reference...I doubt I will be in any silly seas in the near future. Fairish weather only unto such a time as I have the experience to confidently.handle a bit of weather.

And I haven't a chance of getting out without the boys for now...will take some time for the novelty to wear off them, I'd imagine.
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Old 18 July 2015, 09:55   #8
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Do you have power trim (or could you manually trim down when he is ringo-ing...)
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Old 18 July 2015, 10:08   #9
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Quote:
Originally Posted by davidni View Post
The boat planes very very quickly. It's just my youngest is comfortable at what I consider a very slow speed and it would be good to just get that nose down a touch more without causing issues elsewhere.
bag of sand /container of water in the bow?
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Old 18 July 2015, 10:14   #10
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Quote:
Originally Posted by Poly View Post
Do you have power trim (or could you manually trim down when he is ringo-ing...)
Its just manual trim.

Tbh the boat seems to go well trimmed 2 up. Power trim would be nice to be able to adjust as conditions change.

Trimmed ot right down for it. But the speed he's confident at is really too slow to expect the boat to keep its nose down without some sort of additional help.

And when its nose up for long periods, it seems to drink a bit more fuel.
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