I'm listing; talk to me

[Ronald1]

I recently purchased a 1969 Sea Sprite 15' trihull with a 1970 60hp Evinrude. When running at 2/3 to wot it lists to port about half a bubble. The boat tracks in a strait line but lists noticeably. It also seams more "surefooted" turning to port than starboard. What can be done?<br /><br />The hull is shaped like an older v-bottom, flattening out towards the rear. The two forward hull projections are not nearly as pronounced as some tri-hull designs. The interior is very spartan so I'm guessing the hull to be fairly light.<br /><br />The Evinrude 60 is equiped with a 13.25X17 OMC aluminum prop and a stingray hydrofoil. It does not have power trim. It seams to excellerate briskly and tops out at 27mph according to my 1969 speedo. I have no tack but it sounds right at wot. The antiventalation plate is slightly lower than the bottom of the boat, maybe 1/2", and the center of the hydrofoil kicks up a rooster tail. I think the hydrofoil may be causing more drag than good.<br /><br />Any advice or opinions are appreciated.

 

[cobra 3.0]

Re: I'm listing; talk to me

I had a similar problem when I first bought my boat(a 1986 Peterborough bowrider)and moved my battery to the opposite side. My hydrofoil had been mounted a little off center too and I corrected that(I would try it without the foil to see if it changes anything). It still lists a little to port sometimes, but just a little.<br /><br />My boat sits on a trailer all week until I take it boating, so I'm not sure if my foams could be water-logged. (I don't know the history of my boat.)

 

[Jdeagro]

Re: I'm listing; talk to me

Capt. and Cobra;<br /><br />The list is caused by the prop torq. The prop is rotating clockwise and the resistance at higher speeds is enough to make the boat lean in the oposite direction ( counter clockwise). This is further exagerated by the hydrofoil which causes a bow down attitude when cruising. Hydrofoils continue to lift more and more the faster the boat runs. This cause the boat to pitch forward and bow steer. Since the boat is already prone to a list, it is then exagerated. Turning to port is also more agressive and will make the boat lean hard in the turn. It is likely to lean hard to the starboard side also but not quite as hard.<br /><br />In addition, the fact that the cavitation plate is a bit low means that the hydrofoil is also low, which will increase the problem. you may want to raise the motor an inch and remove the foil. <br /><br />Without the foil the boat is likely to be slower to plane, but the handling once on plane should be better.<br /><br />If you want everything, better hole shot, No low speed wander, lower on plane speed, better tracking and handling, better ride, and more top speed do a search on Smart Tabs in this site.

 

[quantumleap]

Re: I'm listing; talk to me

Since the boat is new to you, I would also rule out the possibility of waterlogged foam which could be causing the abnormal handling. But I agree w/cobra and nautiJohn, the foil is probably causing most of the problem.

 

[Chris1956]

Re: I'm listing; talk to me

Captain, You might try moving the tilt pin in the outboard's clamp bracket up one hole. If it is too low, you can get "Bow Steer", which can easily cause a listing condition. <br /><br />PS If the engine ventilates in straitaways or turns, the tilt pin is set too high!

 

[BillP]

Re: I'm listing; talk to me

If the boat bottom is flat enough, you can raise the motor (read foil) to be above it at planing speeds. That will keep the lift at low speeds for better hole shots...and give no bow down problems at high speeds. Mine is set up this way and the foil helps me trim higher and run faster.

 

[JasonJ]

Re: I'm listing; talk to me

Mine tilts to port a bit at full throttle but I don't really care , I don't run full throttle very often, just once in awhile to work the motor a bit. Its just prop torque, trim tabs will fix it if it really bothers you.

 

[Ronald1]

Re: I'm listing; talk to me

Thanks for the advice! I think I will try raising my motor and loosing the whale tale. The engine was mounted one hole higher on the transome at onetime as evidenced by the marks left behind. I wonder why it was lowered? I think it needs to be raised. <br /><br />The boat ran fastest when trimmed up to the third hole. Hole shot is better in the second hole. Having only 60hp to work with I'm worried about the holeshot more than top speed. My wife tried to ski (very little experience) and it seamed to pull ok. It's hard for me to judge how hard the boat is pulling without trying to ski behind it (my back is screwed up right now). I hope I can loose the hydrofoil and keep my holeshot.<br /><br />From what I read the Smart tabs look very appealing. I do not have power trim. Will these give me some of the effects of power trim? This is an old boat and I hate to keep sinking money in her....but... Can I take the tabs with me if I sell the boat?<br /><br />Thanks

 

[Jdeagro]

Re: I'm listing; talk to me

Captain Tuna;<br /><br />Power Trim is usefull because it allows you to use the thrust of the prop to change the attitude of the boat. It is most usefull when used in conjunction with trim tabs as you will then have two methods of adjsuting boat attitude.<br /><br />The problem with depending solely on the trim of the motro(yours is fixed and not adjsutable from the throttle) is that it uses prop thrust for something other than propulsion.<br /><br />Trim tabs adjsut the hull design (surface)to compensate for the changing conditions such as speed, waves, load, etc. This allows the prop to do only one thing - propell.<br /><br />There is nothing more effective for improving the overall performance of your boat than trim tabs.<br />If you choose to buy Smart Tabs the model you should use on your boat is ST980-40 which are sold on iboats. They are currently out of stock but a shipment is on the way to them as we speak. Wait a few days!