"new" boat is porposing

[klaypigeon]

I just got a boat, finally! My "new" boat is porposing like crazy. I think it is compacting my spine. It is an 89 smokercraft challenger (16'3" 76" beam) with a 1976 evinrude 70 3-cyl. Also hanging off the back is a 9.9 Johnson whose extra weight may be the source of the problem. I do not have power trim and the engine is trimmed in the second to last hole. If I back it all the way down the engine will be pointing downward due to the negative angle of the transom. (sorry if I don't know the lingo yet, just trying to explain best I can).

It does fine at 1/3 throttle, but any thing after that it starts bow slapping like crazy. Once I reach WOT it levels out a bit.

So I figure I could overcome this if I had power trim but I dont know if that is available or affordable for this old of an engine or should I just yank the 9.9 off? I kind of like the security of it but I don't really do that much trolling. I would be way better served by a bow mount troller. Pics attached.

Your thoughts would be appreciated.

[Ship of Fools]

you just buy that off Craigslist?? ..... i saw that boat listed.

it seemed like too low a price ..... maybe this is the reason it was so cheap?

you could always try to take the small motor off just to see if it helps .... otherwise someone with a little more boat knowledge will hopefully chime in

there are boating / boat repair forums where you may get a better answer

[Roccus]

Moving the tilt pin closer to the transom will change the attack angle of the bow.. it will plane faster and ride flatter with less squat..

[klaypigeon]

I can move the tilt pin to the first hole, but like I said on a plane that will now have the engine pointing downward. I am thinking she will start plowing, but there is only 1 way to find out...plowing may be preferable to slapping anyway. I decided I am not going to pull the 9.9 until I am more confident the 70 isn't going to leave me adrift, at least a few more trips.

@Ship of Fools: ya, I did just buy it off craigslist. When all was said and done I paid $2300 which seemed more than fair. I will probably sell the Johnson and the downrigger I got with it eventually and add a bow mount troller. The hull is an old design; tried and true - but I don't think it was designed to have a second outboard hanging there. This is a relatively short and light boat. Kind of like putting a 200 pound dude standing on the transom.

[Roccus]

most boats that size do well with a 50 HP motor... just adjust the tilt pin to give you the most comfortable ride... the previous owner may have had more weight ( people) in the bow.. thus his way of compensating was to move the tilt pin away from the transome...to acheive more bow lift... the reason the motor is adjustable is to compensate for differant transdome angles and boat loads.. you will have to find the motor angle that best suits your needs.

[klaypigeon]

It's a lot better. I think I lost a little bit of speed off the top end, but 32mph is plenty fast for me. The ride was a lot smoother with it trimmed all the way down, but I also had a 250lb dude in the boat with me instead of my girlfriend. Thanks for the advice.

[fishhunterboyz]

Had a similar problem with my boat. Added a stabilizer to the motor and solved it immediately. Also gained gas mileage and top end speed.