Hydrofoils worth the bother??? - Page 2

Superjetjim · 19 July 2015, 11:21

I removed a set from a motor I purchased and had capitation issues - turned out the drill holes in the anti cavitation plate (these were the older style Doelfins that required drilling) were venting air directly above the prop allowing it to slip wildly at lower speeds - I taped the holes up with gaffer tape as a test and the slipping vanished. So lesson learnt for me - if you remove a set or see holes left from when a previous owner had a set make sure you plug them with a decent epoxy metal filler.

jonp · 19 July 2015, 12:45

Quote:

Originally Posted by Poly

Given that the involve drilling holes in the anti ventilation plate no manufacturer is going to warrant them. I've never seen any official guidance from a manufacturer suggesting bearing issues, have you? Can you share it with us?

If they were universally great then manufacturers would offer different leg designs with bigger plates built in. That they don't tells me that they arent needed by a big part of the market.

Im going by what new outboard dealers have told me, Ive bought 4 new engines in the last 5 years. We get 5 year warranties (on most brands) and have the weather where people tend to put hundreds of hours per year on there outboards which may be the reason manufacturers tell us not to fit them. My rib Ive only owned for a couple of months is just having its 100hr service this week and this is mid winter when I dont use my boats as much (its also one of 2 boats I own which both log around 300hrs per year).

As we've seen with many things on here things are much different in regards to regulations etc, it seems a little silly for me to contact manufacturers in the UK to ask if they warranty outboards with fins fitted. As for here you will be told by any new outboard sales person.

Over here we have a much larger boating community than the UK even though the population is much smaller

Maybe over there manufacturers have no problems honouring the 5 year warranty, why not ask.

Jon

Poly · 19 July 2015, 14:41

Jonp, I'm not seeking a warranty on an engine (with or without Fins) so it would be bizarre to go and ask. As a general rule though I discount anything told to me by sales people either promising that something is or isn't covered / required. Now if the engineering department produced a document (although how they would know with Xk59D' no drill ones I'm not sure). I'm not doubting they will refuse a warranty claim, I am just wondering if there is real basis to YOUR claim that fins exert undue wear on the mounting hardware.

Im surprised it's much of a new engine issue, since presumably new engines give you the chance to correctly spec the engine first time. Fins tend to be a solution to a compromise.

Since Dave has a used engine with probably no warranty it's all a little academic unless there is real evidence they harm the engine.

1eyedjim · 19 July 2015, 20:23

I personally don't like them and hate to see holes in a leg where they have been fitted.

But that said I fitted some to a 3 m rib with 15hp that wouldn't plane 4 up and does now so they do have their use

I would only want to fit any in extreme cases though.

For the sake of £25 i would fit some and try it. What doesn't work for someone might work well for you

jonp · 19 July 2015, 23:10

Quote:

Originally Posted by Poly

Jonp, I'm not seeking a warranty on an engine (with or without Fins) so it would be bizarre to go and ask. As a general rule though I discount anything told to me by sales people either promising that something is or isn't covered / required. Now if the engineering department produced a document (although how they would know with Xk59D' no drill ones I'm not sure). I'm not doubting they will refuse a warranty claim, I am just wondering if there is real basis to YOUR claim that fins exert undue wear on the mounting hardware.

Im surprised it's much of a new engine issue, since presumably new engines give you the chance to correctly spec the engine first time. Fins tend to be a solution to a compromise.

Since Dave has a used engine with probably no warranty it's all a little academic unless there is real evidence they harm the engine.

As I said right at the beginning the handling issues Ive had in fibre glass hulls wouldn't happen with a rib, a rib wont let you bury one side of the boat in side swell.

Checked both my Suzuki and Yamaha warranty books and both have a disclaimer that anything fitted to the engine which is not standard can void the warranty (this also includes the wrong pitch prop).

The bennett tabs Ive fitted to 3 of my boats all improved performance greatly across the board. Being able to put more pressure to one side of a glass boat (what Ive used them on) and stop proposing etc were a quick easy fix, they also made the boats feel like much bigger boats in rough sea handling.

With an engine that doesn't have electric trim I would be very cautious of what I put on it, at least the Bennett's have 3 different pressure settings. If the foil brings the nose of the boat down to much your only choice is to take it off and fill the holes. My rib handles badly with to much nose down trim.

Poly · 19 July 2015, 23:31

Quote:

Originally Posted by jonp

... and stop proposing etc...

Certainly many a person here will suggest that proposing ruined the enjoyment of their boating!

beamishken · 19 July 2015, 23:51

As an alternative to fins why not temporarily block the flooding hull & see if that helps with your youngster it might be your just not going fast enough to dump the hull & hence the nose up attitude
I've used Doel fins to good effect but they do seem to be a marmite thing
Can't imagine any damage to the engine other than a couple of extra holes though so for 25 quid probably worth a go

Biggy · 20 July 2015, 00:02

I have the Stingray Junior fitted to my Suzuki, Its made a hell of a difference to my sib.

It planes straighter, at lower speeds, very little bow rise on hole shot..
A remarkable improvement, and with the solas stainless added at the same time, Oh Yes!!!!

il corvo · 20 July 2015, 10:16

as for warranties and such i cannot comment,

but on a personal note over the years i've had a few small (sub 5m) boats from...

a flatacraft force 3 (not the gt) with a 9.9hp on the back, doelfins fitted after not wanting to plane with 3 people. fitted em, planed well and solo cavitated far less in tight turns.

avon SR4 with old classic 50 merc (45hp) again with and with out the boat performed better with the fins, pulled skier out well and cruised at lower revs for far longer,

fletcher arrowflyte 14 with 75hp 2 stroke no doelfins fitted. had PT&T so was easy to trim out and never needed them.

now have avon supersport s3.45 with 40hp 2 stroke, without doelfins was very skittish regardless of trim (manual) so fitted some fins, now is planted and stable, the arse lifts better getting on to the plane.

for me (and this is just my opinion) smaller boats and smaller engines without PT&T do benefit from the fins. the manual tilt can only do so much and weight distribution is even more important. even more so for equivalent 4 stroke engines which weigh 20% more on the transom, the extra lift proved cannot be a bad thing.

the proof is in the pudding and an SR4 that wouldn't pull up a monoskier (me at 20 when i was skinny) without the fins to being able to with them with no other adjustments speaks volumes. you may loose a knot or two at the top but that's no biggie in reality cos nobody pins the throttle 100% of the time. real world cruising and comfort mean more (to me)

as for manufacturers not fitting fins as standard, how are they to know what application the engine will be employed or what boat they will be bolted on. they simply try to the best they can for the majority of usage.

il corvo · 20 July 2015, 11:51

oh, additionally i bought these ones...

HYDROFOIL STABILISER FINS FOR 4-50HP OUTBOARD ENGINE, FISHING, RIB, BOAT | eBay

they are angled up a few degrees so follow the V of the hull better and are quite small unlike the standard doelfins. these are rated up to 50hp.

not the best photo but you get the idea and bolted on as far back on the cavitation plate as possible so the rear edges of the fins are level with the aft edge of the cav plate.

Budgie1 · 20 July 2015, 13:28

I used doel fins on my previous hardboat (Arrowflyte + 60hp) for the very reason in OP, big help meant I could plain towing ringos and kneeboards at about 13 knots (depending on size of the rider) but appreciate they dont work for everyone, I would suggest trying some divers weights up front (bags with lead shot in them) very little space needed for them, if that doesnt work try the doel fins

On my RIB now have Starfire hydrofoil (lot more expensive), you dont have to drill cavity plate to fix them on and sit right over back of cavity plate, plus some divers weights up front but did this for different reasons .... the boat was a nightmare in rough seas far to quick out the hole and bow rise was scary, combination of starfire and a bit of weight boat is now far better balanced but have lost a couple knots at WOT

jonp · 21 July 2015, 03:52

Quote:

Originally Posted by Budgie1

I used doel fins on my previous hardboat (Arrowflyte + 60hp) for the very reason in OP, big help meant I could plain towing ringos and kneeboards at about 13 knots (depending on size of the rider) but appreciate they dont work for everyone, I would suggest trying some divers weights up front (bags with lead shot in them) very little space needed for them, if that doesnt work try the doel fins

On my RIB now have Starfire hydrofoil (lot more expensive), you dont have to drill cavity plate to fix them on and sit right over back of cavity plate, plus some divers weights up front but did this for different reasons .... the boat was a nightmare in rough seas far to quick out the hole and bow rise was scary, combination of starfire and a bit of weight boat is now far better balanced but have lost a couple knots at WOT

Did you put the fins on because the boat handled badly or your power trim doesn't work. If its the boat in your bio you seem to have plenty of power and a modern engine. Its good you dont need to drill them, they look very much like the se sport which does need drilling.

A trick I did on a boat years ago was to stick a strip of something like this http://www.bunnings.com.au/zone-hard...ramp-_p4430023 under the edge of the stern using silkaflex, I only needed a small strip about 8ins each side to bring the nose down. This way you can experiment with the length needed by starting off with a small length, you can also apply longer lengths to one side if the boat leans (cost effective and it works). The boat I used it for was a 4.75 aluminium boat with a Yam F50 which leant to one side and wouldnt trim down quite enough.

Jon

Budgie1 · 21 July 2015, 07:55

Trim works fine but even trimmed right in it was a nightmare. Touch the throttled and it was off like a scolded cat! Great fun on flat water but bit scary in the rougher stuff .... Have no doubt there are other possibly better solutions but mine handles very well now so won't be trying to fix it

Blue Man · 22 July 2015, 19:34

Quote:

Originally Posted by davidni

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.

It sounds like your rib is already working great, but your youngest son just needs to become more confident in the water. Don't change your boat. Help your son become a strong, confident swimmer. That will be a lifelong blessing for him.

No offense intended by the way.

Budgie1 · 22 July 2015, 22:41

Completely different ball game Blue man ..... Even if very confident swimmers can still lack confidence when being towed ... Know from experience can be very painful getting them going but once they get going they are fearless 😳😳

dave3235 · 23 July 2015, 09:59

Hi all

You could try Permatrim foils from Australia ment to be pretty effective.

longjohn · 23 July 2015, 10:16

Stingray Stealth transformed my boat - can now plane at 10 knots and provides instant holeshot particularly when towing ringos and skiers - throughly recommended.

longjohn · 23 July 2015, 14:59

Fitted in minutes with no drilling of the car plate

Force 4 Marine Dynamics Stingray Stealth 2 Hydrofoil

davidni · 24 July 2015, 11:06

Quote:

Originally Posted by Blue Man

It sounds like your rib is already working great, but your youngest son just needs to become more confident in the water. Don't change your boat. Help your son become a strong, confident swimmer. That will be a lifelong blessing for him.

No offense intended by the way.

Not a bit of offense taken. I wanted honest opinions in all shapes and forms.

You are correct. The little rib does run well...like a bullet in fact. And he does need to gain some confidence. This is more for my own benefit to be honest...until he gets to that stage.

I don't think I'm overly keen to start drilling into the cavitation plate if there are drill free options.

I think its definitely going to be either Nauticus sx smart tabs or one of the NO DRILL hydrofoils. Judging by everyone's replies and further research elsewhere...it seems that those who have tried either route have been very happy so I guess its going to be toss of the coin really as both will work out similar price. I can get either at almost exact same price.

Just have to find them some better wetsuits now as their current ones just don't seem to be doing the trick!

Nick Hearne · 24 July 2015, 14:17

I have run various biats with these fitted as with real life People want to sit at the back where you do not want all the weight! They work very well at getting the nose down and planning at lower speeds

BUT I think you need PTT to get the best out of them.
I have a SR4 with a Yam 50 hp with PTT and have used this for towing water skis and toys for me I blocked off the hull as in the harbour at 6 to 8 knots is is a right pain dropping on and off the plain, + 5 plus of us in it and it ends up very stern heavy with the foils fitted I can get the nose down,. If it is me blasting about the Solent I have taken them off and it runs with out any problems with the holes in the cav.plate.
I do not like fitting them but they do a very good job if they are needed, my Ribeye 6m dose not have them and I have never needed them.
Have a 6.5m hard boat with a inboard with I fitted them to as again could not get the nose down with out them and all the passengers wanting to sit at the back.