Underpowered. Will fins help?

[fireman57]

Just rebuilt a 15ft fiberglass runabout. Had a 25hp on a 14ft deep/wide aluminum jon boat that would run about 25mph with three guys in it. New boat is heavier and I can only get on plane with 2 guys in boat. Will putting the "fins" on the bottom of the stern (I have heard them called hydrofoils as well as other things) help me plane? I know I am underpowered now but cannot find a reasonably priced 40 or 50hp engine. If it won't help then I will just wait until I find a different engine. Boat is rated for a 50hp.

 

[Laddies]

Re: Underpowered. Will fins help?

try a prop with less pitch

 

[fireman57]

Re: Underpowered. Will fins help?

I considered that but I'm afraid that I will lose a lot on the top end and I still need to get across the lake and the mighty Ohio river. If anyone can allay my fears I will try it.

 

[Jdeagro]

Re: Underpowered. Will fins help?

Fireman57;<br /><br />The hydrofoils will help the boat plane simply because you are adding additional planing surface to the boat. The more surface the more effective. However the down side will be that they tend to lift more and more as the boat increases in speed. This will drive the bow down at crusing speeds, which will result in more resistance, slower top end, and bow steering in corners. Stability port to starboard is likely to deteriorate because the extra lift is centered on the keel creating a teeter totter effect.<br /><br />If you can only afford the hydrofoil, that is one option. If you can afford to step up to trim tabs (Smart Tabs) for about $150.00 then check them out (search Smart Tabs on this site or others). They are fully automatic and designed for smaller boats. You will be able to plane with three people no problem, and the overall handling will be significantly better. You will think you stepped up to a 40 HP.

 

[fireman57]

Re: Underpowered. Will fins help?

NautiJohn that sounds a lot better. I have to have good handling as these big waters get pretty rough at a moments notice. I've heard of trim tabs but never investigated. I will now and thanks to both of you.<br />Now for my edit. I checked them out and smart tabs seem to be the way to go. However, the only drawback I read was when you are in reverse they pull the sterm down with them as there is now way to raise them out of the way. I saw Bennett tabs but no discussion of the difference between the two.

 

[tonyscj5]

Re: Underpowered. Will fins help?

Does anyone else have any input on the smart tabs effect on reverse. I am also considering trim tabs, but dont want to shell out a butt load of cash for adjustable tabs. Its seems that tabs which are down all the time would kill your reversing.<br /><br />How big of a deal is it? Do they suck the transom under?<br /><br />Anyone with experience please speak up.<br /><br />Thanks <br />Tony

 

[richg99]

Re: Underpowered. Will fins help?

I don't do a lot of reversing, but when I have, I haven't found any particular bad effect. I have SmartTabs on my two boats.<br /><br />You are reversing at slow speeds...that is a LOT different than when you are planing at fast speeds. If some negative effect while reversing were to actually be an issue ( I doubt it )..the SmartTabs instructon book shows a simple way to dis-engage the tabs with a pulley system. I haven't found the need to add that simple solution yet, though. RichG Tx

 

[Jdeagro]

Re: Underpowered. Will fins help?

Fireman & Tony;<br /><br />First of all you both should know that We are the manufacturer of Smart Tabs, however we try hard to give everyone the best informantion.<br /><br />Now to answer the question regarding reverse. The tabs are deployed when the boat is going slow or at rest. That deployed angle is typically 25 degrees. To make it more understandable the trailing edge os the plate (back) is only down about 2 3/4" from the leading edge (transom end). Since power boats are not designed to go mmore than a few miles per hour in reverse (transom pushes water) the deployed position of the tabs do not draw the stern down or inhibit steering in reverse. You simply do not go fast enough in reverse to make them a factor.<br /><br /><br />Note: If the Smart Tabs are set at a more steep deployed angle (more than the 25 degrees) they can and likely will restrict reverse. <br /><br />If you have a jet drive boat (insted of a prop)there is the potention for inhibiting reverse if the tabs are too far inboard (close to the jet pump). What happens is to go in reverse the jet does not change it's rotation like a prop, insted there is a "Gate" (defector) which drops down behind the jet nozzel redirecting the water forward. This pushes the boat backward. If the Tabs are in the way, the reverse water thrust bounces off the tabs and inhibits reverse. It should be noted that jet drive boat do not back up well to start with, so most owners are not concerned.

 

[fireman57]

Re: Underpowered. Will fins help?

John I thank you for the info. I am ordering them from iboats as they have the best price. Thanks for supporting this site. I'm very proud of it.

 

[tonyscj5]

Re: Underpowered. Will fins help?

nautijohn-<br /><br />Do you sell them to the public or must I go through the dreaded middle man who is going to jack the price up?<br /><br />thanks for the advise.<br /><br />Tony

 

[Jdeagro]

Re: Underpowered. Will fins help?

Tony; <br /><br />We can not sell direct as the costs would far out weigh the mark up that the retailers charge. It is not just the shipping charges, but state Sales taxes, accounting cost reporting and paying these taxes, and setting up the warehousing to handle individual orders. I would look at iboats and I think you will find the pricing to be very good. By the way, our raw material costs on stainless steel increased four times last year, but we did not dare to pass all this on to the consumers. If you are going to buy anything made of stainless steel this year do it soon. In some cases the costs have already been increased in others it may have just started.

 

[Jdeagro]

Re: Underpowered. Will fins help?

Fireman;<br /><br />Your welcome and I am sure you will be very happy. Please let us know your results, and if you have any questions please do not hesitate to call us (800-233-0194).