Motor stops peeing due to spun prop?

[cameronfoskey]

Alright guys I'm new to iboats, I recently bought a 16 foot Carolina Skiff with a 50 hp Johnson 1998 model. The issue I am having with seems like a spun prop but not really sure so I'm coming here before I buy a new one. It seems like it "slips" sometimes which makes me believe its a spun prop, but one weird thing that I cant find any answer to is right when you hit a certain rpm it stops pissing, usually right before it gets on plane, I thought the motor sat to high on the transom so I lowered it down one slot which is the lowest. Went and ran it and it seemed that the slipping got a little worse and the pissing did too. The motor recently had a new water pump impeller installed. Is it possible for a spun prop to cause the motor to stop peeing or do I have something more catastrophic going on. Any and all help is greatly appreciated.

 

[Philster]

Re: Motor stops peeing due to spun prop?

I'd prefer pics and or specs as to where the prop centerline is in relation to the transom/bottom of boat.

Seems when getting on plane your water pickups aren't in the water. You run the impeller dry and now it's on borrowed time, too.

Spun prop issue would be unrelated, but maybe you are so high it is just the prop ventilating, since it is way to high to bite. So, yeah, an engine that is too high will stop sucking water on plane and the prop would feel like it is slipping, except instead of slipping around the hub, it is slipping around what little water is there at the surface.

Pics... level from the side. Can you upload them to photobucket or something and link to them? If not, full boat description and pics of the engine, prop, etc... so we can see how it is setup. (new members can't add pics directly to posts).

Everything so far screams: Engine height is too high!

The AV plate above the prop should be somewhere around even with the bottom of the boat (for a starter, baseline setting, etc).

Or, if she stops peeing before planing, the odd angle of the boat might cause a valley/gully at the stern which drops water below the intakes.

This is why pics are valuable.

Another thought: The motor should be down/in all the way, as far as trim is concerned. It should be tucked in tight and not trimmed out at all for getting on plane.

 

[Texasmark]

Re: Motor stops peeing due to spun prop?

Agree with Phil. The slipping you are referring to could be ventilation whereas the prop is sucking air from the surface and adding it to the water the blade is supposed to be pushing which is solid, air compresses. Doesn't surprise me on that boat.

I ran a Carolina once in S. Louisiana I rented with a 60 Merc. It was probably 17' and very wide with a very distinct but shallow v, triple v hull. The thing I noticed was first the prop on the engine was too low in pitch and at WOT it just screamed. However hole shot was neck snapping. I can only guess that they propped the rig like that deliberately so that when you did a hole shot in the marsh most of the time the first 30' more or less was plowing mud and you wanted to get her up as fast as you could.

Anyway, with the boat being that big, wide, and a bottom that was essentially flat, it planed out in a heartbeat and once up and running it seemed to set it's own running characteristics. PTT didn't have that much effect on hull attitude. So I can see sucking air could be very possible.

HTH,
Mark