Reply
 
Thread Tools Search this Thread Display Modes
 
Old 08-18-2017, 09:31 AM   #1
Senior Member
 
Ex Sailor's Avatar
 
City: Toronto
Country: Canada
Join Date: Nov 2015
Posts: 271
15 HP / 2 St. Yamaha

Does anyone have " first hand " exp. with these fins ( or whatever they are called ) that you often see on smaller outboard motors ? I've talked to a few people at the marina and some swear by them and most just don't know and I certainly would not take the word of the guy selling them .....

We have a Alum. bottom 10.5' RIB but it takes a bit to get up to plane ....

Thanks in advance ....... F.B.
__________________
Advertisement

Ex Sailor is offline   Reply With Quote
Old 08-18-2017, 11:44 AM   #2
Guru
 
djmarchand's Avatar
 
City: Litchfield, Ct/Punta Gorda, Fl
Country: USA
Vessel Model: Atlas Pompano 23
Join Date: Aug 2012
Posts: 4,782
I suspect that you are talking about something like the Doel Fin. These bolt to the cavitation plate and act similarly to a trim tab. They work!!!

I had a 9.9 hp Tohatsu on a 10' RIB. It would only plane with two on board. As soon as I added our dog or even a couple of bags of groceries, it wouldn't plane. The Doel Fin solved that.

Another fix that has about the same effect as the Doel Fin is a flatter pitched prop. When I added both, the boat would easily plane with three people and our dog on board and the engine would operate at a higher rpm which was good for it.

David
__________________

djmarchand is offline   Reply With Quote
Old 08-18-2017, 01:36 PM   #3
Guru
 
Jeff F's Avatar
 
City: Great Lakes
Country: Canada
Vessel Name: Mazurka
Vessel Model: Mainship 34 Original
Join Date: Nov 2015
Posts: 595
I have that motor on my Avon RIB310. It had stabilizers when I got it, but I broke one off when putting the motor into storage. Now with one the only think I've noticed different is that it doesn't plane off as well with a load. So I have some anecdotal evidence of their effectiveness.

Agree with David on the prop. I played with three different pitches on mine, and settled on a 10", but I rarely have more than two people in the boat and am mostly solo. If I was loading it any more I'd go to a 9" and that definitely makes it easier to pop up onto a plane.
Jeff F is offline   Reply With Quote
Old 08-18-2017, 01:47 PM   #4
Guru
 
mbevins's Avatar
 
City: Windsor
Country: Canada
Vessel Name: Keeper IV
Vessel Model: 44 Viking ACMY
Join Date: Nov 2013
Posts: 1,305
I have that motor on my 10' RIB .
As said above, they work and are worth the money.
Definitely easier to plane.
__________________
"The democracy will cease to exist when you take away from those who are willing to work and give to those who would not."

mbevins is offline   Reply With Quote
Old 08-18-2017, 06:40 PM   #5
Veteran Member
 
Join Date: Jun 2015
Posts: 82
Quote:
Originally Posted by Ex Sailor View Post
Does anyone have " first hand " exp. with these fins ( or whatever they are called ) that you often see on smaller outboard motors ? I've talked to a few people at the marina and some swear by them and most just don't know and I certainly would not take the word of the guy selling them .....

We have a Alum. bottom 10.5' RIB but it takes a bit to get up to plane ....

Thanks in advance ....... F.B.


Doel Fin and derivatives are an absolute must on a RIB. Cheap to. Put it on and you will be forever impressed!!!
Joebad is offline   Reply With Quote
Old 08-21-2017, 09:09 AM   #6
Guru
 
City: LI or Fla
Country: USA
Join Date: Jul 2013
Posts: 1,106
Just as an added reference, we have a 10.5' RIB, tried using our 8hp Yami 2 stroke, would plane with two people anything else (dog) nada, tried the fin's and still no good, just not enough HP, but like others have said with 9.9 and fins is a pretty good combo.
Marlinmike is offline   Reply With Quote
Old 08-21-2017, 10:12 AM   #7
Guru
 
koliver's Avatar
 
City: Saltspring Island
Country: BC, canada
Vessel Name: Retreat
Vessel Model: C&L 44
Join Date: Nov 2007
Posts: 3,127
Yes!
I had a 10.5'RIB that I bought separately form a Yammy 20 (the dinghy was rated 20hp).
With only me in the boat, initial acceleration was dangerously close to inverting the boat, by driving the transom under the bow.
I put one of those fins on and eliminated that problem, but on initial acceleration with only me in the boat, the bow wouldn't come down to where I could see out. With a sevond person, weight forward, all was well.
I out a set of these: Smart Tabs Trim Tabs Improve Boat Performance on and solved all trim problems immediately. The boat would rise onto a plane with no raising of the bow whatsoever.
I now have a 12' RIB with 40hp that has enough bow weight that I don't need the smart tabs, but I do still have a fin on the cavitation plate to keep the bow from rising.
__________________
Keith
koliver is offline   Reply With Quote
Old 08-21-2017, 10:27 AM   #8
Guru
 
jleonard's Avatar
 
Join Date: Jun 2008
Posts: 3,461
I have a Yamaha 2 stroke 15 on a 10.5 RIB. No extra fin necessary. Gets up and boogies in very little distance.
I did remove the stock prop and went with the next lower pitch to get there.
__________________
Jay Leonard
Attitude Adjustment
40 Albin
Mystic,Ct. /New Port Richey,Fl
jleonard is offline   Reply With Quote
Old 08-21-2017, 10:52 AM   #9
Guru
 
Russell Clifton's Avatar
 
City: Anacortes Wa.
Country: usa
Vessel Name: Sea Fever
Vessel Model: Defever 49 RPH
Join Date: Sep 2012
Posts: 578
On a previous 12 foot aluminum skiff with a 15hp Honda, it would take some effort to get on a plane, and then it would porpoise real bad. Putting a hydrofoil on the motor took care of everything. I have one on my current 12 foot skiff also. Just bought a 15 foot Arima with a 60 hp. , had the same issues with getting on a plane. The hydrofoil took care of it too. Worth the money.
Russell Clifton is offline   Reply With Quote
Old 08-21-2017, 03:34 PM   #10
TF Site Team
 
City: Westerly, RI
Country: USA
Vessel Name: N/A
Vessel Model: 1999 Mainship 350 Trawler
Join Date: Jan 2014
Posts: 1,771
Just keep in mind the hydrofoil is providing lift on the outboard, not the hull. The lift is being transferred to the hull by the motor mounts on the transom. That connection wasn't actually designed for the lifting forces being applied.

Make sure you crank down on your screw clamps.
Shrew is offline   Reply With Quote
Old 08-21-2017, 05:41 PM   #11
TF Site Team
 
FlyWright's Avatar
 
City: California Delta and SF Bay
Country: Sacramento, CA, USA (boat in Vallejo)
Vessel Name: FlyWright
Vessel Model: Marshall Californian 34 LRC
Join Date: Apr 2008
Posts: 12,301
They come by many names....hydrofoil, doel fin, whale tail. They work well in providing needed lift at the transom to assist in getting on plane.
__________________
My boat is my ark. It's my mobile treehouse and my floating fishing cabin. It's my retreat and my respite. Everyday I thank God I have a boat! -Al

@DeltaBridges - 25 Delta Bridges in 25 Days
FlyWright is offline   Reply With Quote
Old 08-21-2017, 05:51 PM   #12
TF Site Team
 
Baker's Avatar
 
City: League City, Tx
Country: Texas
Vessel Model: Carver 356
Join Date: Oct 2007
Posts: 6,250
Same engine here on a WM310 RIB. Like everyone has said, they make all the difference in the world.
__________________
Prairie 29...Perkins 4236...Sold
Mainship Pilot 30...Yanmar 4LHA-STP...Sold
Carver 356...T-Cummins 330B
Baker is offline   Reply With Quote
Old 08-21-2017, 10:07 PM   #13
Senior Member
 
TowLou's Avatar
 
City: Flanders, NJ
Country: USA
Vessel Name: Bassey
Vessel Model: 17' Bass
Join Date: Aug 2016
Posts: 187
The fin did well for a faster planning with a i/o i think 135 hp merc 4 cyl 19' 1984 grady white bow rider.
TowLou is offline   Reply With Quote
Old 09-07-2017, 06:51 AM   #14
Guru
 
City: kemah
Country: USA
Join Date: May 2015
Posts: 1,135
Quote:
Originally Posted by koliver View Post
I out a set of these: Smart Tabs Trim Tabs Improve Boat Performance on and solved all trim problems immediately.
That website is ridiculous. You use the selector wizard or even the chart to find the trim tabs and both suggest a part number. Easy.

Then armed with the part number you go to the buy now page and all tabs are listed by dimensions with ZERO part numbers to be found anywhere. Ridiculous.
what_barnacles is offline   Reply With Quote
Old 09-07-2017, 07:08 AM   #15
Guru
 
Dougcole's Avatar
 
City: Carrabelle, FL
Country: USA
Vessel Name: Morgan
Vessel Model: '05 Mainship 40T
Join Date: Jan 2008
Posts: 1,161
Quote:
Originally Posted by Shrew View Post
Just keep in mind the hydrofoil is providing lift on the outboard, not the hull. The lift is being transferred to the hull by the motor mounts on the transom. That connection wasn't actually designed for the lifting forces being applied.

Make sure you crank down on your screw clamps.
Or through bolt it if you leave the motor on the transom most of the time. That's what I did with my 20hp 'zuki. It helps a lot.
__________________

Dougcole is offline   Reply With Quote
Reply

Thread Tools Search this Thread
Search this Thread:

Advanced Search
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off





All times are GMT -5. The time now is 05:33 AM.


Powered by vBulletin® Version 3.8.8 Beta 4
Copyright ©2000 - 2019, vBulletin Solutions, Inc.
Search Engine Optimization by vBSEO 3.6.0
Copyright 2006 - 2012
×