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Old 01 October 2013, 15:11   #1
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Hydrofoil fins for a 25hp evinrude on rib

Hi, i have an xpro 380 rib with a 25hp evinrude (tiller) and was wondering if hydrofoil fins would be any good?
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Old 01 October 2013, 15:47   #2
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Hi, i have an xpro 380 rib with a 25hp evinrude (tiller) and was wondering if hydrofoil fins would be any good?
Good for what? do you have a problem?

Welcome to Ribnet BTW
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Old 01 October 2013, 15:51   #3
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Would they be benificial in any way, stability? Speed? Bow rise? Planing speed? I have limited knowledge on these.
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Old 01 October 2013, 16:03   #4
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Unless you have a specific problem e.g. stern heavy/bow up I wouldn't bother. Even then there are better solutions e.g. moving weight around, trim etc. I've never been convinced with fins/hydrofoils. Just IMHO of course.
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Old 01 October 2013, 16:10   #5
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Well my problem is when towing a ringo, the engine has plenty of power to do it as it did on my old boat (4m sib) but it seems to stick badly in the holeand not plane until you move everything and everyone to the front and then it planes, would the fins help this or is there something else?
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Old 01 October 2013, 16:15   #6
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Fins *might* help (at the expense of a bit of top end speed.) Trimming way in will help. Lightening the load will help. You already found out that balance helps.

jky
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Old 01 October 2013, 16:17   #7
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Would they be benificial in any way, stability? Speed? Bow rise? Planing speed? I have limited knowledge on these.
I have used them on my 4m rib with a 30hp yam with no power tilt
they reduce overall speed due to drag
on my rib they lower my planing speed, useful for me on windermere where there is a speed limit.
on my boat they reduce bow rise, and the boat rises on to the plane quicker.

as others have said they have many disadvantages, I don't use them all the time
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Old 01 October 2013, 16:20   #8
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I'd say a 25hp is probably on its limit with a 3.8m rib & towing a ringo. What prop do you have on it & are you getting max RPM at WOT? You should be somewhere around 5500rpm
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Old 01 October 2013, 16:33   #9
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I have a 10X13 stainless prop and i do get max rpm at WOT, was thinking weather a 10X15 may be better?
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Old 01 October 2013, 16:37   #10
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Quote:
Originally Posted by xs 400 View Post

I have used them on my 4m rib with a 30hp yam with no power tilt
they reduce overall speed due to drag
on my rib they lower my planing speed, useful for me on windermere where there is a speed limit.
on my boat they reduce bow rise, and the boat rises on to the plane quicker.

as others have said they have many disadvantages, I don't use them all the time
I go out of Saundersfoot, south wales and there is 10 knot speed limit for a km and then no limit, not to bothered about top speed just the bow rise and planing speed, so they seem to work for you.
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