Im lost where should my motor sit

[fishtricker]

hi I have a aprox 1973 17.5 foot mark twain bow rider and have been fighting with the motor the kept on running away and over heating got to thinking about it and saw the previous owners had reinforced the transom with pressure treated 2 x 12 on the out side doubled up and metal plates on the inside looks they rasied the motor about 9 inches the problem is that right before i get on plane the motor comes outta the water at 25 mph or so motor is a 73 jhonson v4 crossflow 115 so i guess my question is where should i cut this 2x12 plate so i dont have to worry any more

 

[Cadwelder]

Re: Im lost where should my motor sit

A picture would help here....but the cavitation fin should be even or slighter above the bottom of the boat.

 

[fishtricker]

Re: Im lost where should my motor sit

um ok im not sure what the cavatation plate is but top of my hub of my prop is about even with the keel would this cause my motor to come out of the water sorry no pics but my computer is prolly the slowest ever and im on dial up

 

[Cadwelder]

Re: Im lost where should my motor sit

This is an older thread but had a good picture of proper height for you.

http://forums.iboats.com/showthread.php?t=193962&page=1

 

[fishtricker]

Re: Im lost where should my motor sit

thanks. is what i have going on prop slip my cavation plate is probally 4 inches higher the the bottom of the boat would this cause the prop to slip or come out ofthe water

 

[Cadwelder]

Re: Im lost where should my motor sit

It very well could, have you checked the props hub? It could be slipping there too. You may be better off having this post moved to the propellers section, as those guys are more up on this type problem than us restore guys.

I can PM a moderater and get it moved it you like.

 

[fishtricker]

Re: Im lost where should my motor sit

i dont think it slips in the hub i have checked all that the motor seems to come up out or close to out then it screams also this is the second motor to do this overheated the first one beyond repair . the transom seems sound is there a test i can do to tell cause i would love to just get rid of the 2x12s all togther they really look goofy and it looks like someone gnawed out a place for a out board in them

 

[Cadwelder]

Re: Im lost where should my motor sit

Well again, pictures would really help here, but if 2 x 12's have been added for support that a sure sign of a bad transom. Does the tell tale hole have a good stream of water coming from it?

Hate to sound like a broken record, but we really need to see what we're dealing with here.

 

[fishtricker]

Re: Im lost where should my motor sit

from what im told this motor was one year prior to telltales so it just kinda spits water vapor just fine and stays cool the other was the same way could run allday on ears i will see what i can do for pics could take a really long time if it happens at all but i can try thanks

 

[HOOKED.UP]

Re: Im lost where should my motor sit

Hi Fish.

As far as I am concerned your motor is too high.

For best performance the plate needs to be about 1/2 inch below the hull, or level with the hull.

I also question all the timber/backing and would look for a problem.

Paul.