4700 rpms and going nowhere

[hartge]

Hi,

I am new to the forum and boat my 1st boat.

I have a 91' Wellcraft Eclise 186 bowrider. I took it out today and it took forever to actually get going, it has a 3.0L in it and the motor sounds fine, starts ups no issue indelies nice enough to troll if I want but when i give it throttle the motor sounds like it wants to go and the rpms go up to 45-47k ish. but the boat is like a piece of lead. I thought the speedo was broken before it actully creaped up to 15-17 mph.

Any help or advise? I only had myself my wife and 2 kids, 9 yr and a 4 yr old.

Shouldn't this boat do close to 40mph. The water was like glass as well.

Thanks

Angelo

 

[oops!]

Re: 4700 rpms and going nowhere

hi.......welcome to iboats.

sounds like you have coupler problems.
that is not prop unless you have a bad hub......but i would doubt that.

 

[hartge]

Re: 4700 rpms and going nowhere

thanks what a coupler ? Cars and BMW's we can talk all day. Boats I'm trying to learn quick. the prop looks like a plane jane 3 blade prop.

 

[steelespike]

Re: 4700 rpms and going nowhere

I'm not an I/O expert but I believe the coupler is in the area where you might find a clutch
and it connects the motor to the drive.They do fail but from your description I think you might smell burning rubber.Do you trim down for hole shot?
If you read "read this first" at the top of the page and get us as much info as possible
it will help figure things out.In the mean time see if you can get it to plane move some people to the bow.Be sure it is in excellent tune,timing right and advancing as it should,
bottom clean and smooth,Throttle opening all the way.

 

[hartge]

Re: 4700 rpms and going nowhere

Here's what I know so far. I am having someone check he numbers on my prop.


1) Performance issue you are trying to correct. - Boat rev's up to 47k ish, but does not go faster than 17 mph, crazy slow off the start even with trim up. Boat this big sea-ray stabilizer thing on the back
2) Current prop manufacturer, model, aluminum or stainless as a minimum. - will find out, looks like a regular 3 blade
3) Current prop diameter and pitch (required).
4) Wide open throttle RPM and speed with an average load (very helpful) - 47k and 17 mph
5) Engine/drive make, model, year, and HP - 1991 merc 3.0l
6) Boat make model, year, length and weight - 91 wellcraft eclise 186 bowrider - 19ft

hope this helps.

 

[steelespike]

Re: 4700 rpms and going nowhere

You need to be trimming down for hole shot gradually trimming up as the boat planes.
While the Foil(stabilizer thing)can help get on plane and stabilize ride.If installed
wrong or poorly matched to the boat it can create lots of problems.One would be that when trimmed up for hole shot,instead of down, could actually cause the stern to dig in.
The foil is there for a reason and its very likely a bandaid covering up a sick motor or boat,
or a poor setup. Sometimes poor storage will allow the boat to absorb water in the flotation foam normally would just cause sluggish performance. But could contribute to other existing problems. The I/Os weak point is hole shot but healthy and setup right hole shot is good and the 3.0 should hover around 40.

 

[hartge]

Re: 4700 rpms and going nowhere

maybe I'll try and remove the stabilizer, when I go to turn it's like driving a 79 volvo without powersteering. wouldn't the boat eventually get up to 40 or close to it. The boat starts everytime,idles smooth, oil is clean as well as motor, no leaks or leaking gaskets.

BTW thank you for all the input so far.

 

[hartge]

Re: 4700 rpms and going nowhere

the stabilizer is a stingray classic. should I take it off?

 

[hartge]

Re: 4700 rpms and going nowhere

here are the numbers I was able to get off the prop. this is how they are listed on top of each other

A03521
07011
A00293

Does that mean anything to anyone.

 

[steelespike]

Re: 4700 rpms and going nowhere

Do you trim down for hole shot?
Do you smell burning rubber when trying to plane?
I don't recognize those numbers. Usually near the base of the blades or under the prop nut
will be mumbers for diameter X pitch _ _ X _ _ . Could be a 21" pitch.
That might make planing sluggish a but fairly easy.

 

[hartge]

Re: 4700 rpms and going nowhere

ok well i went out today and found that my trim up was sticking and not always going up when I hit the botton. Ran much better. the prop numbers are 48-78120-19. I need to get a new prop, which one should I get. Also what max rpm should I be running the boat?

thanks

 

[steelespike]

Re: 4700 rpms and going nowhere

The 19 stands for a 19" pitch I don't have the info for the other numbers.
That is a Mercury number you can probably look it up it will give diameter and material.
When selecting a prop; pitch is the primary consideration. If you select a prop intended for your boat the diameter will follow.
Without your present performance numbers we can't tell if your present prop is working.
The 3.0L is listed at 115 hp so it may struggle a little more than the 135hp LX.
The L and LX have the same 1.98 gear ratio so the L will likely use less pitch and I would guess the 19" pitch is about the max for decent performance.
Your final selection would depend on the present wot rpm and speed and your typical load and activities.