Getting on plane

Family Isle

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I have a 06 Gufstream 250 HP fourstroke. With three or more fishermen,equip,gas,ect.. I cannot get on plane. I had a 96 gulfstream 250 two stroke that got on plane. I've remounted the engine 1'' higher, checked the prop for re-pitch, use the trim tabs and trim nothing works I'm frustrated and embrassed with guests on board. I tried to deal with the factory help line to no avail. Both boats I purchased new one in 96 and one at season end in 2006, so this has been going on since spring of 07. I never took the second one for a test ride because I was so happy with the first one. Anyone have some ideas? Regards
 

wahoo33417

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Family Isle: First, welcome to the forum. I'm afraid i don't have a good answer, but maybe a suggestion. Try posting this in the "Tips and Modifications" section. You're likely going to get the attention of the many single-engine Gulfstream owners there. Also, you may want to clarify what you mean by checking the prop pitch. What is your engine rpm and boat speed at wide open throttle?

Rob
 

gwwannabe

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My guess is that you have too much prop for the load you're trying to push. Your new 4 stroke motor doesn't have the torque that your previous motor had and probably doesn't have the same HP at the prop, especially if it can't turn up to the recommend RPM range. I had a lot of trouble planing with my Gulfstream when I first got it and raised the motors (3 holes), changed props several times, and finally got the trim process down. Now, before accelerating, I lower the trim tabs all the way and tuck the motors all the way in to the transom. She comes up quickly and then I start raising the motors to raise the bow. How much I raise the motors and how much I raise the trim tabs depends on water conditions. I reverse the process as I slow down to keep the boat on plane as long as possible.

For any of us to help much, you have to provide some additional info.

First step is to record max rpm and speed with a normal-for-you load at wide open throttle. Also record the speed and RPM where you get on plane, your cruise speed and RPM, and the speed/rpm where you fall off plane.

Next, with a full load record the max speed and rpm you can obtain.

What is the diameter and pitch of your prop?

Gary 93 Gulfstream w/ twin 140 Suzuki 4 strokes
 

geoklic

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I have a 1990 23' Gulfstream. Just repowered with twin 150 Yamaha 4 strokes. Ran the original Yamaha 150 HP 2 strokes for 15 years. Excellant engines. They finally got too old. The new 4 strokes do0 a decent job getting up on plane. It becomes tricky when trying to navigate in 4' seas without constantly throttling up and down. I think thats the minimum power for these boats. Contrary what everyone says, the only advantage to 4 strokes vs 2 strokes is the fuel economy. The 2 strokes develop the power much quicker; they do the work in 2 strokes vs 4 strokes of the engine. Unfortunately the 250HP 4 stroke will only dissapoint you no matter how much you raise the engine or how many props you try. Put a smaller prop on and you may get out of the hole quicker only to sacrifice top end speed. A lose lose proposition. If the engine was a 2 stroke it might be different. Incidentally the HP rating on the 150HP 4 strokes is either overstated or measured differently from the 2 strokes.