boat stallling in the water
07-25-2004, 08:54 PM
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boat stallling in the water
hi everyone,
I recently just took ,my boat out to the lake yesterday nd this morning, nd tested out my boat that's never been run before but has been kept in storage for a VERY long time. So recently i took it out, painted it, maintenanced it, put in some new stuff and so forth. So i go out nd it's fine i guess but it's got some speed changing problems. for example if u accelerate it fast then it will choke nd stop, nd if u decelerate it, well, it does the same too.
So i thot it was bcuz water was gettin into the air filter, nd so i made a make shift shield to prevent water from getting in, and it worked so that's no longer my problem
but the main reason that im posting is that this is a K&B 3.5 engine by the way. Anyways, so im cruising down the lake at full throttle nd i make a turn, but it's got sensitive response so it makes a sharp bank either in the left or right direction, but once it makes that quick sharp turn the boat stalls in the water at full throttle nd goes no where while the engine is still runnin, nd then u bring the throttle down nd itll jump off the water nd start going again, nd it keeps doing that. ANy answers to this problem? it's as if there's no water around the propeller and it just spins before water starts to spill into it. The acceleration is weak also. How do i fix that? Thanks.
I recently just took ,my boat out to the lake yesterday nd this morning, nd tested out my boat that's never been run before but has been kept in storage for a VERY long time. So recently i took it out, painted it, maintenanced it, put in some new stuff and so forth. So i go out nd it's fine i guess but it's got some speed changing problems. for example if u accelerate it fast then it will choke nd stop, nd if u decelerate it, well, it does the same too.
So i thot it was bcuz water was gettin into the air filter, nd so i made a make shift shield to prevent water from getting in, and it worked so that's no longer my problem
but the main reason that im posting is that this is a K&B 3.5 engine by the way. Anyways, so im cruising down the lake at full throttle nd i make a turn, but it's got sensitive response so it makes a sharp bank either in the left or right direction, but once it makes that quick sharp turn the boat stalls in the water at full throttle nd goes no where while the engine is still runnin, nd then u bring the throttle down nd itll jump off the water nd start going again, nd it keeps doing that. ANy answers to this problem? it's as if there's no water around the propeller and it just spins before water starts to spill into it. The acceleration is weak also. How do i fix that? Thanks.
07-26-2004, 03:27 AM
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RE: boat stallling in the water
This phenomenon is called cavitation.
If you keep the power on after a snap turn, the high revving prop has problems getting a grip on the water, because the boat speed has dropped.
Regards, Jan.
If you keep the power on after a snap turn, the high revving prop has problems getting a grip on the water, because the boat speed has dropped.
Regards, Jan.
07-26-2004, 12:05 PM
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RE: boat stallling in the water
Cavitation happens when a prop spins too fast for the water to maintain laminar flow over the blade surfaces ... the flow separates and air bubbles form and join, creating a pocket of air in which the prop will spin freely. When you back off the throttle a bit, the prop slows down and the air bubble escapes, re-attaching the flow to the blades and the boat 'takes off' as the prop begins to generate thrust again.
That is an over-simple explanation, and not exactly the way it works (the full technical details are more complex) ... but the gist is there. If you do a web search for cavitation whole bunches of material are returned ... google was down when I checked, but yahoo had a couple of good sites.
Hope that's helpful.
Jonathan
That is an over-simple explanation, and not exactly the way it works (the full technical details are more complex) ... but the gist is there. If you do a web search for cavitation whole bunches of material are returned ... google was down when I checked, but yahoo had a couple of good sites.
Hope that's helpful.
Jonathan
