Trouble Planning

[f-pelton]

Ok. I need some help.
I have a 13' Boston Whaler SS Limited ('87)
2003 Yamaha 4 stroke.
No stingray or dolphin on the motor.
I bought the boat over the winter and have been trying to get it to run to optimum performance. With one person, it gets up pretty well and does about 28-30.

With three people and 9 gallons of gas, it doesn't want to get up on a plane.

Couple of questions about planning...

Even if if doesn't want to get on a plan, should the RPMs be up? When she is working to a plan, should the motor be around 4,000? When she is trying to get up, it is almost as if it just doesn't have good low range power. Once on a plane, she moves right along at 5,500 rpm.

I rebuilt the carbs a few months ago and changed the plugs. I brought it into the shop and they did a link and sync on the carbs with vaccum guage. They said they ran it in the water and it ran great (however, it was probably with only one person).

Should I next get a dolphin/stingray?

Am I expecting too much out of this motor?

Is there something else that I should be checking>

With what I read about a 13 footer with a 40, I feel like I am just not running the way I could be.

Looking for advice. Thanks,
Bob

 

[steelespike]

Re: Trouble Planning

4 strokes generally have a little harder time getting a load on plane.
You are pushing a pretty good load 3 adults=450.motor close to 200 lbs,gas
and battery another 110 so you can figure 750 to 800 lbs if your hauling any other gear.If you have the battery and gas in the rear thats almost like having a a person sitting on the transom. If possible move battery and gas forward even if only to the middle.Trim the motor in(prop closer to the boat)
Another problem is the little boat, it's harder to get the load up on top because of the relatively small planing surface.A hydrofoil should be a last resort,and something like Smart tabs would be a better solution if there is room to mount on the stern.After trying all else you could try a foil I like the Doelfin.
It will definately help you get on plane and stay on plane easier.
just go easy until you see how it acts.They sometimes cause wierd handling.

 

[Rancherlee]

Re: Trouble Planning

Whats the redline on your motor? You probibly should be running a different prop with that much of a difference in weight. I find the opposite to be true of 4 strokes, they seem to be less picky about added weight then carbed 2 strokes.

 

[JUSTINTIME]

Re: Trouble Planning

if a F40
u need 5000-6000 rpm
i would shoot for 5800

 

[f-pelton]

Re: Trouble Planning

Thanks for the replys. I have been out of town and away from the PC.

Over the winter, I brought the prop to a prop shop and asked them to knock it down a few degrees. I just checked the prop and I noticed that they stamped my name on it and "P15". I am assuming that means the pitch is 15. I can't imagine that it was a 17 pitch.
I am wondering if that is still too much pitch for what I am trying to accomplish?
What pitch/size prop are typical 40 4 Stroke Yamis using? I do think that I carry a fairly heavy load.

Should I be looking for 5000 rpms while "trying to get on plane"? I do hit 6000 once on plane, but the boat runs great then.

Thanks,

Bob

 

[Windykid]

Re: Trouble Planning

I had a 13' whaler (1964) and a 35 evenrude (82) it had a 15 pitch and ran 5500 RPM,s and had no problem getting up on plane with a full load and haul butt. It was also sensitive to distributing the weight.