Boat wont plane out

[william66]

I have a 14' alum v bottom pretty simple 2 benches with seats, trolling motor with small battery. 5 gal. gas tank, 26lbs of anchors the motor is a 1970 johnson 9.5 hp with new coils, new points and condensers, new plugs, and a clean carb. with a 8 x 8 1/4 3 blade prop. it will start every time on 2 or 3 pulls and seems to run smooth on bottom and top end but it will NOT plane out ! my buddy has a 14' 6 wood and fiberglass v bottom with a 9.9 merc. which has to be a heavier boat and it does just fine ??? mine will not plane with just myself and im just about 160 lbs so am I missing something or asking too much for what it is ? should it plane or am I just short on hp ( I know I know ) im short about 10 hp lol.

 

[RandyJ]

Re: Boat wont plane out

I'm running a very similar boat with a 9.8 hp Mercury, no problem planing out. Every time I've seen this problem it has been that the motor is tilted too far rather than being somewhat straight with the transom. Another thing I've seen is just too much weight in stern end of the boat. I put anchors and gas can as far forward as possible so my boat will plane faster. My son is a pretty big guy about 225... he sat up front this morning when we went fishing and I started to ask him to move back to the next seat so we would have more speed with a little lift to the front end. Weight distribution is a really big part of getting a boat to plane out. Power and speed are big factors but not as significant.

 

[william66]

Re: Boat wont plane out

I have tryed to trim it in all 6 slots and although it does make a difference it still not enough not even by myself and im pretty sure it should plane out then thats why i wonder if i am missing something or something isnt tuned just right so im not getting the last little bit out of her ???

 

[Silvertip]

Re: Boat wont plane out

Is the engine actually running on both cylinders?? It's amazing how many folks can't tell, even on a two cylinder engine if one cylinder is dead.

 

[Home Cookin']

Re: Boat wont plane out

I agree about the cylinders.
Otherwise, take someone with you and have him move around to see what helps--start towards the front then move back.
Running across shallow water will also lift a boat but I don't know if it will work on one that small. This is a trick for sand or mud bottoms!

 

[RandyJ]

Re: Boat wont plane out

Well then, If things are as you say then I'd say the problem is with the motor. If the boat goes fast enough it will get over the swell of water that the boat creates and rides on top of. This swell of water acts like a pivot point and moves toward the transom as the boat accelerates. Once the crest of this swell is far enough back the weight of the boat pulls the bow down. It is the thrust that pushes the boat to keep the nose up. Seems to me that your motor is not pushing it fast enough to overcome the wave which is lifting the boat. For all I know the guys are right that you may not be hitting on all cylinders or other power robbing problems.

 

[Jeep Man]

Re: Boat wont plane out

Does the motor appear to rev in the proper range. You may have a damaged or spun prop. Try a different prop, even one of the same size and pitch, and see if there is any change.

 

[william66]

Re: Boat wont plane out

I have checked and rechecked the points plugs and carb and they all seem to be in working order and running on both cylinders . does anyone know of a test tac. or way to rig one up ? its hard to tell if is running at top rpm just by sound with it being so small and fairly quit ? there are only 3 prop options for it right now it has a 8 x8 1/4 3 blade on it next size down is a 8 x 7 3/4 3 blade then a 7 x 7 1/4 2 blade ? whats the chance it could be the leaf blocks week or broke down maybe ? I know they can make a world of difference on the power ban of a 2 stroke dirt bike ? thanks to everyone !

 

[bonz_d]

Re: Boat wont plane out

There is an item called TinyTach that attaches to a sparkplug wire. Supposed to work very well though I have not tried one.

I once had a setup like yours with a 1969 9.5hp Johnson (still have that engine). The hull was rather narrow and with 2 adults and a child it would have a hard time planing. A wider hull would've done better because there would have been more lift from the hull. I would guess going down a prop size would help.

 

[steelespike]

Re: Boat wont plane out

Tinytach is a good idea but if your not planing your not making much rpm.
Check the link and sync.Unhook on plug wire at a time and see if it runs.
Have you checked compression? Are the plugs burning evenly. a brownish black look
not shiney or velvet black.Is one plug much cleaner than the other?

 

[pootnic]

Re: Boat wont plane out

Have you ever taking all the weight out...that you could?
Might plane then...
How about waterlogged foam(floatation),is that a possiblity?
How is the hull(underneath)especially right before the prop...no big dents?

 

[william66]

Re: Boat wont plane out

the plugs look good the old boat is exactly 14' long and the beam/ width is 59 at the widest point 1/3 of the way back and tapers down to 54" at the back it is 20" deep in the frt. and 16" deep in the back with a slightly rounded bottom? so who sells these tinytachs ?

 

[saumon]

Re: Boat wont plane out

install a whale tail (just joking)!

 

[bonz_d]

Re: Boat wont plane out

so who sells these tinytachs ?

Online only I do believe though I could be wrong.