Doel-Fin

[JimCt]

Considering installing Doel-fins on my Merc. 75.  Have read these improve fuel consumption & stabilize hull motion.  Problem I'm trying to fix is that with one or two people at the console at speed the boat rocks fore & aft in a regular motion.  Nothing severe, but it's there.  Motor trim won't iron it out.

Several makes of hydrofoil are available.

Need opinions, reviews, cautions and an education.

[Tailgunner]

I installed one of these and love it. I don't know about the fore & aft motion but it did make a difference with performance and gas consumption. I also installed the torque stabilizers to stop the pull to starboard. It worked. I bought the Sting Ray version. I would do it again.

[JimCt]

Thanks TG!

Torque stabilizers?  Haven't heard of them.  My boat has a severe pull to starboard too which I've been able to cut down some with the engine tab & increasing the Teleflex drag, but its still there.

[Tailgunner]

Sting Ray sells torque stabilizers to go on their fins. They sit underneath and are adjustable. Much like the tab on the outdrive. They are around $15.

[JimCt]

Thanks TG!  Will look into getting them.

[frank1861]

I had a doel fin on my 170 it didn't seem to make a diffrence with the fore and aft motion (porpuising). The only thing that fixed was triming the engine all the way down, but your going to lose top end. I think you should look into a set of tabs to really fix the problem.

But if you want to try a stablizer fin one step better then the hyrdofoil or doel fin is the bobs stablizer plate its made out of alluminum so it doesn't bend like tradtional stablizer fins.

http://www.bobsmachine.com/Products/transom_stabilizer.cfm

[Tailgunner]

I agree with Frank. If you can afford them (I couldn't at the time) trim tabs are the way to go.

[scott_gunn]

Trim tabs would be ideal, but a Stingray stopped my 200 from porpoising.  It also helps stay on plane at lower speeds and I have less bow rise during takeoff.  Lost a little bit of top end speed.

[John Jones]

Trim tabs are best but any of the cavitation plate fins help.  I had a Bob's Machine Stabilizer Plate on my last boat.  It's basically the same but aluminum.  Helped with hole shot, porpoising, lower planing speed.  It has so little drag there was no noticible difference in top speed.  What I like about Bob's plate is it reinforces the cavitation plate instead of stressing it like the flexible ones.

http://www.bobsmachine.com/Products/tra ... ilizer.cfm



I took it off before I sold the boat.  $20 and shipping gets it.  Fits Yamaha and Mercury.

[RickK]

Jim, I had a Doel-fin for many years on my 'rude and it worked great - so good that I forget why I really bought it.  I think it was hard to get it on plane (hole shot) and our boats like to sink into the water at or under 20mph for some reason.  This helped with this slower speed planing. You can see it on the old 'rude here

I had a Bob's Machine Stabilizer Plate on my last boat.  It's basically the same but aluminum.  Helped with hole shot, porpoising, lower planing speed.  It has so little drag there was no noticible difference in top speed.  What I like about Bob's plate is it reinforces the cavitation plate instead of stressing it like the flexible ones.

http://www.bobsmachine.com/Products/tra ... ilizer.cfm

I took it off before I sold the boat.  $20 and shipping gets it.  Fits Yamaha and Mercury.

I have the same problem with 2 people behind the console with this motor - unless I jam it, it doesn't want to plane out easily.  I wanted a little beefier hydrafoil this time so I bought one of these 2 weeks ago and I installed it last weekend.  This weekend looks like it will be nice enough to test it.
BTW it's $42.75 to your door now.

[John Jones]

Good deal Rick.  Did you know that if you pull your boat up to Ruskin they will put it on for free?   I think you will like it.

[Mr. Osprey]

I got a doelfin an my 75hp merc and it runs great. No porposing and great hole shot when I blast the throttle. Not sure what kind but I can check if you want.

[JimCt]

J.J., Please hold that hydrofoil aside on the shelf with my name on it.  My Personal Hydrofoil Tester, Rick, will evaluate the performance for me ...      .

It will fit my '03 75hp Merc., correct?  Any special hardware needed for mounting?

Rick, If you happen to be wandering around the back end of the 170 with your camera, could you squeeze off a few shots of it so I can get a look at the foil?  All I've seen is the ad picture from Bob's Machine.  (I'll pay for the film... )

Just for funsies I took a look at the Lenco & Bennet sites.  Nice gear.  I can afford them but I dont want to afford them if I don't have to.  If I can squeak by with J.J.'s foil I'll be a happy pilgrim.

[John Jones]

Heck Jim, I'll even give you a money back guarantee as long as you pay the shipping back to me if you don't like it.  

I'm pretty sure I bagged the hardware that came with it.  I don't think I have the instructions anymore but maybe Rick could copy his for you.  All you will need is a tube of silicone rubber sealant that Bob's recommends to use when mounting.  I used gray because it was on a Yammie.  You can even get black for the Merc.

When I bought it Bob himself told me it was designed for a Merc but would fit a Yamaha.

[John Jones]

I dug up some pics from the last boat.





Now I remember what Bob told me.  He said to fit it on a Yammie I might have to grind out the plate to clear the zinc tab on the motor but if I remember right, it fit without grinding.