Hydrofoils

[Darrendude]

Are these bolt on hydros any good? Pros/Cons?

 

[tommays]

Re: Hydrofoils

darren<br /><br />on my 20 ft maxium the boat is pretty useless with out one.<br /><br />long time to plane and very high planeing speed with out. <br /><br />forget about trying to go through a heavy chop at a low speed with out them.<br /><br />they are not as good as adjustable tabs and also you lose some top end speed.<br /><br /> but you cant beat the price and they are maintance free.<br /><br />tommays

 

[lakelivin]

Re: Hydrofoils

Made a hugh difference on my 17' bow rider. Also really helped my neighbors 19' bowrider. Planes much quicker with MUCH less bow rise. Also stays on plane at much lower speed than without.<br /><br />You might want to check out the Cobra Marine product if you go this route. It mounts under the cavitation plate to eliminate stress/ breakage to lower unit casing. Plus it is of a different design than most, they claim better results.<br /><br />Can't verify in general, but it works much better than the one I pulled off (I think it was a Sting Ray, but it was pretty old so maybe the co. has improved their design).

 

[Darrendude]

Re: Hydrofoils

Thanks guys

 

[djvan]

Re: Hydrofoils

If you decide to use one make sure you get it mounted perfectly straight, as one made my boat lean (list?) until I got it straight.<br /><br />DougV>

 

[ziggy]

Re: Hydrofoils

they are cheap. i had mine come with the boat i got. below. got stearns brand. $18.95. wow what a deal. they do seem to help get it up on plane though. know this cause i lost port side on a stump on the river. wondered why my boat wouldn't plane out at it's normal speed. didn't know the stump had left me with a hydo stump on the port side. amazingly didn't break the ventalation plate, which after replaceing the broke foil i found has been repaird. and still intack after the impact. if i had to do it and i didn't have a hydrofoil i'd sure think about the smart tabs myself. they sound better to me. even though they aint quite so cheap. sounds like those smart tabs really work good. perhaps a option for ya.....

 

[rwidman]

Re: Hydrofoils

Consider trim tabs instead. Much better. Smart Tabs are self adjusting and cost well under $200.00 for your boat. I installed a set on my previous boat, an 18'Stingray. They were easy to install and made a big difference.

 

[Ralph 123]

Re: Hydrofoils

I have them on my twin Alpha 1s and they work great. They helped my hole shot dramatically, decreased the speed needed to stay on plane, and helped low speed steering. I don't really use my trim tabs any more. My boat is too fast as it is so I can't even tell you if they hurt my top end.<br /><br />So, it depends on your boat. For short money, you can put it on and see if it helps. If it doesn't pull it off and try more expensive tabs.

 

[Johnnydeep]

Re: Hydrofoils

I run hyd trim tabs on my 2150 and even with the tabs my little 4 banger has a tough time getting me up on a plane. Throw a couple of sets of dive gear in and it just would not happen. Put on a D-fin and the difference was dramatic to say the least. I lost maybe 1 mph on my top end of 23mph. But now I can get up on a plane even with three divers and gear and bow rise is non existant, the boat just raises out of the water level, and at a lot lower speed. Just getting out of the hole loaded was worth many times the price!!!

 

[hoot]

Re: Hydrofoils

a large (heavy person) should not use them for a step. have heard stories of plate cracking. have seen several designs, hard one piece, two piece, and rubber.

 

[Darrendude]

Re: Hydrofoils

Jonnydeep,<br /><br />What is a D fin? And where can I get one?<br /><br />Thank you

 

[DJ]

Re: Hydrofoils

Darren,<br /><br />D fin is short for Doel Fin. A brand of hydrofoil.<br /><br />I didn't see them avaialble here on iboats. Do a Google search, something will show up.

 

[Johnnydeep]

Re: Hydrofoils

What DJ said, I have another brand on a 19ft Hammond that I have never run but the previous owner swears by it too!!!

 

[Dunaruna]

Re: Hydrofoils

Gotta agree with lakelivin, the cobra fin (they call it a stabilising plate) made a massive difference to my 23fter, one of the unexpected benefits was that it stopped the low speed wander.<br /><br />Aldo

 

[lakelivin]

Re: Hydrofoils

Dunaruna,<br /><br />I've been surprised that the Cobra Marine products aren't mentioned more when foils are discussed. I think it's because they're such a small company and don't market very well. <br /><br />But I do like the single plate design and the fact that they mount under the cavitation plate to eliminate stress that could crack it. Not only does it help with bow rise and low planning speeds, my boat turns on a dime.<br /><br />I talked with one of the guys at CM when I got mine years ago. He said that some of their retailers were even advertising higher top end speeds, but CM asked them to take that part out because although it might be true for some boats, it wasn't true across the board.<br /><br />For only $50 or $60 bucks, and given the ease in installation, I think a Cobra foil would be well worth consideration for smaller boat owners. <br /><br />I suspect it would give many what they want; if not, outlay is pretty small and they could try something else.

 

[Dunaruna]

Re: Hydrofoils

and they look good!

 

[MrBill]

Re: Hydrofoils

For a few years I was a huge advocate of the hydro fins...or whatever you want to call them. They work great, but after two broken anti-cavitation plates I've given up on them. Maybe on a different drive that hasn't been broken and repaired twice I'll carefully consider one again. <br /><br />Most importantly, get one with mounting holes as far forward as possible and as far away from the edge of the anti-cav plate (or change original mounting holes if possible. The veterans on this board have heard my caution about this in the past. Remember...the hydro foil transfers all the pressure required to keep your bow down via four bolts onto your cav plate and drive...an enourmous amount of force.<br /><br />My first experience with one, I'll admit, was probably mounted too close to the rear and too close to the edge of the drives plate, it snapped when my 240 lbs brother-in-law stood on it. Good thing it was my favorite brother-in-law. It had worked remarkably well and withstood almost the whole season with a lot of water sport activity and holeshots.<br /><br />The second time I chose a different model that had two independent fins. I attached each fin as far away from the plates edge as posible, with particlar care on the side which had been welded. About half way through the season while accelerating reasonably hard with my boat at near capacity the cav plate broke, and not on the side which had been broken before. Myself and most others on the lake where I'm at are reluctant to use them any more.<br /><br />I very much liked the performance gains and quicker planing, but I'm tired of repairing the cav plate on my drive. Leaving it with a huge chip off the rear causes a large rooster tail spray at cruising speed and a slight pull to one side, no vibration but I only tried it two times.

 

[Richard Petersen]

Re: Hydrofoils

Am I getting the picture straight from most of you? Most under 20' bow riders run better with the Hydra foils or trim tabs and anything like them? If so, I now understand why I am building a 18' 2 seat boat that looks like a Gar Wood- Hacker- woodie. 18' by 4' 6" wide, engine is in center of boat. I notice old WW II SCOTT PAINE PT boats had a characteristic of coming up on plane, level at all speeds. Odd, but nice to me. In my I/O 18.5' Chaparral- 220 hp 5.0 L it is a pain to get on plane. And it becomes light at 48 mph. Loss of steering, cavitation easy, all other bad things start to appear.

 

[Jdeagro]

Re: Hydrofoils

Darren;<br /><br />There have been many postsing on this topic which you can find by doing a search on Hydrofoils. You will find many people tha t believe they have helped their boat. You will also find people who have had less than satisfactory results. <br /><br />As the manufacturer of Smart Tabs (automatic trim tabs) you might suspect that I am not a fan of any fixed or rigid planing device including Hydrofoils.<br /><br />They are cheap, and they do add additional stern lift which can help the boat plane, however because they are fixed they permanently change the hull design. This usually translates into reduced performance in another area (such as a loss of top speed).<br /><br />Let us address the issue top speed for a moment. Most people think that the loss of top speed is due to the additional "drag" on the stern. This is not the reason for the loss in speed. What happens is the hydrofoil (because it is rigid) continues to lift the stern as the boat speed increases. This causes excess stern lift and a esulting bow down (plowing)effect. With the electric trim, the boater then trims the motor out to bring the bow up. In order to bring the bow up enough the trim angle is no longer perpendicular to the water surface (most efficient thrust angle) and the loss of thrust results in less speed. In short the motor and prop are fighting the excessive lift of the hydrofoil.<br /><br />Next, if the hydrofoil is running at or below water level (typical of a stern drive where the motor height can not be changed) the hydrofoil will have a tendency to act like a rutter especialy in turns at higher speeds. This can cause the boat to lean excessively in turns unless you throttle back. <br /><br />The next issue is one of lateral stability. By adding additional lift surface directly in the center of the hull (stern drive or out board leg) the lateral stability will surffer. I refer to this as the teeter totter effect. <br /><br />Trim Tabs are installed on either side of the Boat hull, as an extention of the hull. The lift is adjustable (if using a helm controlled system) or in the case of Smart Tabs - Automatic. This means that a the slower speeds the tabs are deployed to reduce bow rise and improve planing, but at cruising speeds they come up as required. All trim tabs that are properly installed will retract beyond the horizontal position so they do not provide excessive stern lift at cruising speeds.<br /><br />Smart Tabs will retract at crusising speeds because the water pressure will exceed the actuator load (spring load). This load can be preset to the exact needs of the boat so that issues such as porpoising can be eliminated, but without the excessive lift that drives the bow down. In our case we instruct that the proper adjustment is achieved when the boat runs 2 to 4 MPH faster than it did without the Smart Tabs.<br /><br />If you would like a copy of our booklet "Boat Balance and Performance" go to our web site www.Nauticusinc.com home page and choose the title from the menu on at the bottom of the list under quick links.<br /><br />One last note: Hydrofoils have been used for many years, and the motor manufactures still do not incorporate the extra large cavitation design. Why?

 

[bigbrownbuku]

Re: Hydrofoils

cobra fins are close to the most expensive you can buy is probably why.