I/O Fin...Will it help

[NCOffSeason]

I'm looking at the Doel Fin for my 18ft bowrider with a 4.3 and Alpha 1 drive. It says it will help with low speed planing and that is what I'm looking for to help pull wakeboarders. I'm not expecting the world for 25 bucks, just some improvement as my boat does pretty good now. <br /><br />Does anyone have any experience with these? Do they work?<br /><br />Is this a direct bolt on or will I need to drill holes?<br /><br />Expensive trim tabs are not an option.<br /><br />Thanks,<br /><br />

 

[rickdb1boat]

Re: I/O Fin...Will it help

Might have better luck posting in the I/O section....

 

[cobra 3.0]

Re: I/O Fin...Will it help

I use a Stingray hydrofoil for tubing/skiing. What a difference! It's up on plane in 1/3 the time and the nose doesn't rise as much on take off. You will notice the ability to do flatter and tighter turns without any cavitating. You will be able to cruise at slower speeds too and will generally be impressed for the measly $25.00 it costs. However, I loose 2-4 miles per hour at top end.<br /><br />I also hear lots of great news with the smart tabs...with no loss on top end speed...The tabs do cost more though.

 

[CharlesW]

Re: I/O Fin...Will it help

We used the Doel Fin for years for trick skiing. The lower planing speed really helped. Before the fin, the speed the trick skiers wanted was just below planing break over point. A skier would pull in the rope, give it some slack to do a turn, boat would pop up on-step and the skier was down. With the Doel fin, that was history.<br />It was a simple slip-on device that we just installed for trick skiing and then removed afterwards. Never had any problems in 6 to 8 years of use.<br /><br />Charles

 

[NCOffSeason]

Re: I/O Fin...Will it help

Will one of these reduce the boats wake?

 

[CharlesW]

Re: I/O Fin...Will it help

Since we very seldom used the Doel-Fin above 10 to 15 mph, it wasn't much of a factor other than the boat wasn't running bow high with the huge wake that comes from that. The few times we ran with the fin at 20 to 40 mph, I don't remember the wake being any different than it was without it. Never really paid that much attention, though.<br /><br />Charles

 

[Jdeagro]

Re: I/O Fin...Will it help

Chris; <br /><br />I must assume that you have a modified or deep V hull. First any additional planing surface you add to the stern area of the boat will reduce the wake. Just FYI.<br /><br />The mention of loss os top speed by cobra 3.0 is common to hydrofoil performance characteristics. Although the loss of a few mph is not earth shaking, what it does tell you is that the foil is causing too much stern lift (not drag)and is pushing the bow down. With tilt trim you can bring the bow back up, however the prop is now trying to compensate for the hydrofoil, and running through the water at an inefficient angle. Thus loss of speed. Any loss of speed at the top end is going to be a loss of speed ( efficiency at low to mid range as well. This translates into higher fuel costs. <br /><br />Your low cost hydrofoil is likely to increase in cost every time you leave the dock.<br /><br />Permnent or fixed planing devices only help under one set of circumstances and / or conditions. Either side of this will be a degradation of performance.<br /><br />Adjustable trim tabs ( like flaps on airplane wings) can be adjusted to each set of circumstances or conditions. Smart Tabs for your boat would be the best and least cost trim tabs at about $170.00. Check this site and others.

 

[steelespike]

Re: I/O Fin...Will it help

I agree with nautijohn especially at higher speeds.But it would seem that if the boat planes at lower engine speeds and you choose to run at<br />lower to mid range speeds you would save fuel or <br /> at least break even.It would also seem that if<br />you are using trim tabs to adjust boat trim there<br />is also some drag involved.Unless you are a speed freak I think the Doelfin is a great way to go.<br /> Ive used them on an 18 ft 120 hp I/O bow rider and a 15 ft 50 hp outboard with exceptional improvement over many years,uses loads and speeds.

 

[Jdeagro]

Re: I/O Fin...Will it help

To Steelespike;<br /><br />If we are talking about helm controlled trim tabs (hydraulic or electric), they may create drag if deployed. For example; when attempting to reduce or eliminate porpoising you would deploy the tabs slightly. This lifts the stern a bit and rotates the bow down (holding down it so that it does not porpoise). This is the same as trimming the motor down to push the stern up and the bow down. <br /><br />Smart Tabs use a nitrogen gas actuator which is under pressure (extended), and allows the water pressure to adjust their position. At Slow speeds they are deployed, and once the boat planes the water pushes them up. However, they are always under some pressure and even when the plates are horizontal they provide resistance to the side to side and bow to stern motion. They act like a suspension system on a car. The system is completely adjustble so that extra or excess lift pressure can be removed to suite the individual boat. Independent editorial tests such as Trailer Boats Magazine (19 ft Maxum with a 5,0 V8) showed an increase in speed at every RPM level from 1000 ( 5.0 mph) to 4600 ( 49mph) with Smart Tabs over the same boat on the same day without Smart Tabs.<br /><br />Give what he wants to do with the boat the lowest / slowest plane speed will be with the Smart Tabs.<br /><br />Go www.nauticusinc.com under product tests and click on the Trailer Boats editorial.