hydrofoils breaking aluminium wings?

jvb · 08 June 2014, 11:22

hi ribbers,
i have good experience with simple hydrofoils on my SR5.4 / DT65.
now i am thinking to add them to my 90Merc too, but i heard they might cause the aluminium wings to break off.
do you have any experienced concerns against them?

its the cheap ones…:

thanks again for forums help!

jan

beerbelly · 08 June 2014, 11:27

my mercury 75 has them don't know if there the cheap ones or not but nothing has broken off in the 5 years iv owned it

Peter_C · 08 June 2014, 17:47

Logic, whether right or wrong, tells me a one piece will be stronger than a two piece. Aluminum will be stiffer than plastic and therefore again stronger.

I have "heard" that they can sometimes break the lower unit, but have never seen the results. It also begs the questions of were they properly installed and did they hit something?

CJL · 08 June 2014, 19:13

I've had ribs with and without them and not really noticed any significant benefits.

Change the engine set up rather then use em!

Chris

jvb · 08 June 2014, 19:20

thanks guys!
well...one has to drill some 4 holes in the aluminium wing that surely weakens it a bit. dont know. vertical force could hit an extended wing quite strong i suppose. well, i try it.
i have noted a difference with/out on the dt65. planes easier and further on the very rear. i preferred it.
thanks again
j

jyasaki · 08 June 2014, 21:01

Quote:

Originally Posted by Peter_C

I have "heard" that they can sometimes break the lower unit, but have never seen the results. It also begs the questions of were they properly installed and did they hit something?

Or try to stand on them.

jky

paintman · 08 June 2014, 21:08

Like this?
Permatrim Marine Limited - Products

Peter_C · 08 June 2014, 21:39

I have used the Stingray brand on a couple of boats. I really like the one on my little SIB as it planes at just under 13mph even with a light load. The wake is far smaller, allowing me to plane in areas I probably shouldn't without feeling too guilty. When loaded with people and dive gear to the gills, I can still plane. With that said I wouldn't put a wing on a 5.4meter boat, but instead look to trim tabs on the hull. More versatility, with the ability to level the boat. That is of course assuming the transom has the room, around any elephant trunks, sonar units, etc. If it were me, I would be doing a lot of research to pros and cons of both systems.

jvb · 09 June 2014, 22:27

the permatrims look proper. mich more solid than the tiny rubbery fins.
will try to get some for mine.
thanks!

Nos4r2 · 09 June 2014, 23:15

Doubt you'll need fins on an SR5.4 with a 90.

Gilles · 10 June 2014, 00:43

had them on a mercury 175 optimax and a ficht 150 never had any issue. but i m not a fan of those things and note sure that it s really usefull and performant ...and for sure not that beautifull

jyasaki · 10 June 2014, 15:42

Quote:

Originally Posted by paintman

Like this?
Permatrim Marine Limited - Products

The Permatrims are built pretty solid, and have the advantage of being a one-piece unit, bolted in 8 places (as I recall) which all together, make for a platform that (by their description) is suitable for use as a step.

I wouldn't try that with the 2-piece fins (like the Doel-Fins.)

jky

paintman · 10 June 2014, 21:01

And work very well. I fitted one to my Mercury 135 V6 (on a 17' Dory) some years ago & haven't regretted it

Had a good look at what was available. Not enough room for tabs & I was dubious about the two piece items. Its a substantial piece of aluminium, simple to fit & nicely finished.
Imported it to UK from the manufacturer although I expect a decent metal works could make something up very similar locally.

PeterM · 10 June 2014, 21:03

Got 300 hours with doelfins on my boat. Use them as step up onto transom with no problems.

jyasaki · 11 June 2014, 01:35

Quote:

Originally Posted by paintman

Imported it to UK from the manufacturer although I expect a decent metal works could make something up very similar locally.

I think they come out of Australia? I seem to recall that when I was looking (still intend on changing mine to a Permatrim, one of these days.)

You are right; should be easy to come up with a knock-off - there's not a whole lot of engineering involved.

jky

paintman · 11 June 2014, 08:11

Mine came from New Zealand. Looking at their websites they have dealers in Australia & a US importer in Wisconsin.
About Us

jyasaki · 11 June 2014, 15:01

SIMYamaha was one of the early US resellers (through the US Permatrim office, I think.)

jky

jvb · 16 June 2014, 10:47

i ordered them from NZL.
will let you know how it went.
thanks for all the info
jan

stigoftd · 17 June 2014, 15:05

had fins on most of my higher speed boats never had any ill efects or breakage
bigest engine i had them fitted to was a mariner 60 elpto and the boat handled so much better [salmon 16 - shetland 536 hull] fuel usage was less and steering alot lighter
all my ribs and sibs have had them on [apart from the present one] only because i use the engine for 2 different boats]
well worth fitting and as some have said can be used as emergency step if a mop ocures [altho i dont thing recommended]

HughN · 17 June 2014, 15:46

[Not surprisingly] fins make power-trim much more effective...