bow bounces

[screenbuzz]

when my boat planes and i start to trim up the bow of my boat begins to bounce. what causes it to bounce. i have an 18ft V with a 115 evinrude with a 13 3/4 x 15 prop. the motor is all the way down in the last hole of the transome. the hydrofoil is flush with bottom of boat. is the bounce a cause of motor being to low. thanks for any help.

 

[BKool68]

Re: bow bounces

When the boat begins to bounce or porpoise it means that you have over trimmed the motor. You can only lift the boat up so far on plane. You need to back the trim off at this point to achieve your maximum efficiency. Your trim position is not a fixxed thing either. Wind direction, current, wave height and the load in your boat can change how much trim you need to get her on proper plane.

 

[Ross J]

Re: bow bounces

I had the same problem which was fixed with a couple of sacks of sand placed in the bow - about 40kg did the trick. It's hardly noticed when towing either!<br />Ross

 

[crab bait]

Re: bow bounces

srceenbuzz.. when you said hydrfoil did you mean hydrfoil or cavitation plate ??

 

[screenbuzz]

Re: bow bounces

crab bait i'm fairly new at boating. this is my first one. not 100% sure what it's called but it's mounted on the lower unit just above the prop. thanks bkool68 and ross for your info. this is a very cool site with losts of knowlegeable people.<br /> crab bait,researched the hydrofoil yes it is a hydrofoil that i am speeking of.

 

[crab bait]

Re: bow bounces

on my boat with " whale tails " & power trim it doesn't take but a mynute touch of the trim switch to get my noise abouncin' without the hydrofoils it can take alot more trim.. actually to answer your question :: all the way down should be no bounce ,, move more up notch ,, more bounce... try removing those whale tails.. see what happends...

 

[aerwin]

Re: bow bounces

I have the same problem with my boat, it starts to porpose, even on the smoothest water. I have and OMC 800 outdrive, I was told it had to be in the all the way down position and it cannot be trimmed due to the gears that have to mesh. will the dolphin type tail attached to the outdrive help?. when on plane where shoud the prop be, slightly forward, perpendicular or slightly tilted back? I could adjust the motor mounts with some shims. any help would be apppreciated thanks Andy

 

[SeaDawg]

Re: bow bounces

draftman, yes, a doel fin or similar "whale tail" type should help.

 

[jwhite]

Re: bow bounces

draftman<br />Your motor has a seperate tilt/trim setup. The engine actually moves up and down for trim while the outdrive moves up and down for tilt. You should have two swithces on the dash or somewhere, one for tilt and one for trim. Never run the boat with the tilt up any at all you will destroy the ball gears that connect the outdrive to the engine.

 

[aerwin]

Re: bow bounces

I know what your talking about with the engine tilt but my does not have this feature. I'll try the doelfin and save for a new boat<br />thanks for the replys Andy

 

[BBogey]

Re: bow bounces

My fin made a huge difference.