71' 9.5, Plane a 12'?

[wind knot]

I have a 12' aluminum 55" beam, 50.5"X16" trans. Motor is running great, but is just short of putting the boat on plane. It has the stock three blade prop. I have the steel 6gal fuel tank in the bow. With me (220lbs) and fly fishing gear(30lbs?). I checked the throttle plate, and it is wide open at full throttle. Would I different prop help to make it plane?.

 

[ledgefinder]

Re: 71' 9.5, Plane a 12'?

The 9.5 should plane that boat easily. Is the compression good (feel like even pulses from both cylinders when you pull start it)? Spark on both cylinders? This is an open 12' aluminum hull right? With 4 passengers it might slowly plane, but with one passenger it should fly.

 

[wayne h]

Re: 71' 9.5, Plane a 12'?

where is your cavitaion plate located. it should be the same hight as the bottom of your boat. also how do you have the tilt.you will need to play around with this and see what works best for your boat i had to add a stingray JR to my cavataion plate. another guy from this sight tryed it also and he had great results from it also i forgot his name hope he writes in.

 

[58BigTwin]

Re: 71' 9.5, Plane a 12'?

Wind Knot,<br /><br />I also have a 9.5 on an 11.5 johnboat. I am alsoabout 220 size and mine will (barely) plane with 2 people my size. I have found that the trim is critical for planing on these small light boats. I use a 8 1/8 X 8 prop most of the time, and found that moving up to a 8.25 X 9 made a noticeable DECREASE in performance. I also have a 2 blade 8 X 71/4 for really heavy loads and for use as kicker on 16 ft johnboat. I am at about 2200 feet here in ID.<br /><br />I would also check out the carburetion. I have found that if the carb is too rich on the idle mixture, it will affect the top end performance.<br /><br />TE

 

[wind knot]

Re: 71' 9.5, Plane a 12'?

Wayne, the cavitation plate is even with bottom of the transom. I've tried different settings on the prop angle. <br /><br />Bigtwin, I'll try your mixture screw suggestion. Where I go fishing is between 3000 to 5000ft. Also, I can't find a stamp on the prop, do you know what the stock size is?.<br /><br />Thanx , Darrell

 

[58BigTwin]

Re: 71' 9.5, Plane a 12'?

Darrell,<br /><br />I think the stock prop is an 8 1/4 X 8. At 5000 feet you will definitely be feeling altitude effects. There should some sort of numbers on the prop hub. If it is a Michigan Wheel prop, there will only be a number, OMC will have the dia and pitch.<br /><br />Good luck<br /><br />TE

 

[Fouled Plug]

Re: 71' 9.5, Plane a 12'?

Wind Knot, you may consider a small hydrofoil for your application. Friend at work has a 12' with an 8hp and fin, and it'll plane. And he's no lightweight!

 

[mav1973]

Re: 71' 9.5, Plane a 12'?

i have a 9.9 evinrude with a 14 ft alumacraft row boat with 3 people in it. It gets up great on in land lakes or 1 fters on lake erie will only have 2 people on it due to the waves wont cut through the water to good

 

[catfish Rick]

Re: 71' 9.5, Plane a 12'?

Hi wind knot, I have the same 9.5 johnson and a 14 ft heavy fiberglass boat and at first mine did'nt plane but now it planes perfect, what I did was I made some make shift trim tabs just like the big boats have,I got (and it worked perfect) one of those clipboards that are metal that have a compartment the width is perfect,and cut it about 7 inches long, make 2 flaps then bend 2 inches and screw them or bolt them into the hull on the back just like trim tabs, when you go on the water just adjust them bending them up or down to get the boat the way you want it to ride, that clipboard metal is perfect it won't rust and its stiff, you'll be amazed how good it works

 

[DJ]

Re: 71' 9.5, Plane a 12'?

wind knot,<br /><br />I think the altitude is DEFINETELY affecting the performance.<br /><br />You may want to consider rejetting the high speed, if it is a fixed jet. Your Johnson/Evinrude dealer will have a chart for doing so.<br /><br />That will help, but it won't give the engine the power it would have at sea level.

 

[wind knot]

Re: 71' 9.5, Plane a 12'?

Hi all, sorry I haven't replied to this thread in a while. There is huge forest fires, burning in our area, and we lost internet service for a few days. I think I'll check with the dealer, on what the main jet size should be, for my altitude first, then go from there. <br /><br />Thanks for all your suggestions. As soon as the smoke clears around here, I'll report back on my progress.<br /><br />Darrell