4000 RPM to WOT, No In Between

[scotthco]

Hi Everyone:

This is my first post. I looked but didn't find this situation anywhere. If there's an existing post on this, please let me know.

We've always owned v-hulls, but now due to a back injury, we're in the market for something with a smoother ride. Today we test drove a 2006 Landau 20' with a 60hp fuel injected four stroke Suzuki. This boat has the u-shaped pontoons rather than the circular type if that makes any difference.

The first thing I noticed was that the throttle handle seemed pretty stiff going into gear and back to nuetral. I'm sure I could get use to that though. The real issue was that, while you could set just about any rpm up to 4000, after that it just sort went from 4K to 5500, which I'm guessing is WOT for that motor. Now at 4K, the throttle handle was nearly all the way forward, so just another small nudge and there you go, WOT. No matter what I did, I could not get the boat to hold any rpm in between 4K and 5500.

Also per GPS 4K yeilded only 8-9mph, and at 5500 the top speed was only 15-16mph. I thought a 60hp should be more like 12-14 @ 4K and 20mph give or take at WOT.

Has anyone else had this type of experience, and if so, what was the cause in your particular case?

I look forward to hearing your comments and suggestions.

Thanks!

Scott
Centennial, CO.

[rancherlee]

06' should still be the BIG 60hp Suzuki which likes to run ~5300rpm for max HP. Usually there is a "friction" adjustment screw on the controls somewhere to adjust how stiff the throttle arm is to push. That motor should be able to push a 18-20' into the low 20's and huge party barges into the upper teens for speed. It may also have sticky throttle/shifter cables which might explain the stiffness OR the cables have too tight of a bend in them along there route to the motor.

[teecro]

I tend to think that your speeds are fairly close to optimal if only down a little. What condition are the toons? If not clean and smooth they will rob you of top end. Also it is my opinion that most U-Shaped toons cost you speed as they are usually slightly smaller in diameter and offer less flotation as a result and they are usually filled with flotation foam for strength and that adds weight, if any water gets in this foam it is also likely trapped and it adds weight...

Your throttle cable at the motor may have an adjustment to correct the non linier movement.

[scotthco]

Thanks for the replies folks! So I've started leaning the other way on the rpm jump thing. I guess that part could be the cable, possibly frayed and stretching inside the sleeve.

However assuming that WOT is supposed to be around 5500, which I'm trying to find out now, the cable thing doesn't explain the relatively low speed at that rpm. Unfortunately I didn't get a chance to check the prop size and pitch while I was there (it's 2 hours from me). However if WOT IS supposed to be around 5500, and it's hitting 5500, wouldn't that mean it's propped correctly and any change would cause it to either over rev or turn too slow?

OH, it just hit me: What if the cable thing WAS keeping it from actually hitting WOT. If that WAS the case, depending on what WOT is supposed to be, I suppose it could be propped wrong.

Here's two other things. Thing 1) I just found out that the u-toons are only 21" diameter, and Thing 2) the lake we tested in is at roughly 6400 ft elevation. Not sure how much those things might reduce the speeds.

[smltooner]

Welcome to the club.
You'll get plenty of info here.