New problems, does they ever ends ? Spunn hub or cavitation - I'm to new at this...

[zymox]

Testing day because my motor has been a real pain in the ... Was out to day on a shinning blank sea and when I added some power to accelerate the boat couldn't plane. It started to act like a worn out clutch on a car, the boat came up to a certain speed and a small raise of the bow then the engine continued to rev but no speed increment.
I took my prop off for a look at the hub and this doesn't seems to be worn out to me. I tried to spin the prop out of the water by hand and it sticks enough to pull the pistons. The rubber-hub seems to be just fine. Also there was no slamming or banging like when you loose a gear and into grip again.Not the fast revving that would appear on a lost gear either, just a smooth revving with no speed incrementation. When I pull back on the throttle it will gain grip again at low speed and loose grip again when at a certain level into plane. Not even close to plain speed though. This hasn't been an issue before and I'm totally out of ideas. Please, all ideas are welcome. I will by a new prop soon but since this hasn't been an issue before I doubt that it has anything to do with the prop. All weight and passengers are as they normal are. Just me an 60 liters of fuel. Added some pictures of the mounting and the hub...

 

[phillnjack2]

Re: New problems, does they ever ends ? Spunn hub or cavitation - I'm to new at this.

Ok now the only way to tell if its a spun hub is to make the prop and mark the rubber hub.
wipe all that grease off the rubber as that is not doing it much good anyway (petroleum eats rubber ).
get it nice and dry and put a bit of white paint on the rubber, just a very thin line, and also on the alloy hub.
then punch it hard and see what happenes,if its spun hub then when you take it off and look there is not much chance of it being perfectly lined up again !!!

But I tell you now, all that algae crap around the gearbox is not doing it any favours and willo not off tons of power.
the water is not getting a nice smoothe path to the prop, the vegetation around gearbox will make the water go all over the place.
ive had a dirty engine case before slow a boat down by nearly 10miles per hour, and only a light boat.

get the trim tabs level as well, trim tabs are to be used for getting on the plane, they are for balance once on the plane and to keep a slower planning speed.
far too many people think put tabs all the way down to get on plane, that is wrong, they are meant to keep the boat level left to right.

is this the usual prop that would get the boat up on plane quick,or is this a different un tested prop / and what size is the engine and prop.
looks like a v4 ,but could be v6


phill

 

[boobie]

Re: New problems, does they ever ends ? Spunn hub or cavitation - I'm to new at this.

Mark the prop and the prop shaft with a straight line. Take it out and run it till it slips and then check the marks. If they're misaligned the hub is slipping.

 

[zymox]

Re: New problems, does they ever ends ? Spunn hub or cavitation - I'm to new at this.

Thanks for some ideas. The trim tabs are mounted as per instructions from Smart Tabs selling them to me. They level out at a certain speed and is only made for making a lower plane level. This ones works just like a chock absorber on a car and levels them self, they can't be adjusted by me during the ride. Anyhow, I can with ease release them to make sure they don't drag to much. Also I will clean of the alga's and paint the surfaces with the same "keep clear" color as the boat. This growth is from only 2 month in water. This can actually be the problem since I used to take the boat out of the water and this was holding it clean but arranged for a permanent place in the harbor instead. A bad idea if not painted correct.

You are right about the motor, it's an Evinrude V4 looper 140hp -1988
The prop is what came with the engine and has worked great with the boat until today. It's stainless steel and marked 88A4 ??9510 -13x19 : the boat is 6 meters in length and older than grandpa so it weight's more than a modern 6 meters boat.