1980 85HP Merc On 14" Fiber Glass boat?

[LAKERJOE]

I bought a 14"Mark 150 Fiber Glass bought with an 85HP MERC OUTBOARD on it . The boat flys but it takes alot to come out of the hole. Is the engine possible to large for this boat? And if it is is there a way of ajusting it so the back doesn't ride to low?<br /><br />Joe

 

[tmcalavy]

Re: 1980 85HP Merc On 14" Fiber Glass boat?

Most boats have a tag that states optimum weight/load and recommended top hp for an outboard. My 15 foot runabout from the 70s isn't rated for anything over 70 hp, at least that's the mfg. recommendation (Ebbtide). Your boat may be different, but you may be overhorsed (Yes, it can occur). If it bothers you, think about swapping for a smaller hp engine with a marina/repair outfit or on Ebay. Just food for thought. Mine runs a Merc 500 5 hp and its fast enough for this BOB (Big Ole Boy).

 

[LAKERJOE]

Re: 1980 85HP Merc On 14" Fiber Glass boat?

Thanks for the info. Only problem I'm having is that the boat maker is out of business, I'ts a Mark 150 made by the image boat company located in Lake Hopatcong NJ. Have any knowledge of this boat?<br /><br />Joe P.

 

[blifsey]

Re: 1980 85HP Merc On 14" Fiber Glass boat?

If your boat doesn't have a capacit tag stating max HP, there is a USCG publication that details a formula to calculate for home built boats. I ran the numbers on my 14' v-utility tin boat and it worked out pretty close to capacity tag. I was thinking of building boat at time and was seeing how to use the formila. There is a Duck Boat Builders page on web with the document in MS Word format. Sorry, I don't have link but a Google search should find it. As far as getting stern up, you could try a adding a fin to the OB. Search for doel fin or fin and you should find several threads on this. Be warned, opinions vary widely on their use. Basically, they are supposed to get boat on plane quicker and at slower speed but sometimes reduce top end. Also, can any heavy items be moved forward (batteries, etc.)?<br /><br />Good luck,<br />BL...

 

[tmcalavy]

Re: 1980 85HP Merc On 14" Fiber Glass boat?

The fin will get you on plane faster and make the boat more stable, but it won't solve your riding low problem. From what I've read, the cavitation plate on the outboard should be about 1 to 2 inches below the hull bottom, when exactly parallel to the hull bottom (in the down and running position). If yours is already set that way, you may have too much motor. You can either live with it and use the top end (fast,fast,fast) sparingly and carefully, or you could explore putting a governor on the engine to limit speed if the top end seems dangerous. Others might know a way to address the riding low issue, but I can't think of any except swapping to a smaller/lighter outboard.