View Full Version : Cavatation
12-11-2001, 07:06 PM
Trying a new motor and its cavatating heaps when l turn,can you just change the pitch of the prop to fix this????
Its probably a stupid question but looking for some new opinions.
Thanks in advance
13-11-2001, 04:03 AM
The correct term is ventilation (has everything to to with air) but even the "anti-ventilation plate" gets called a "cavitation plate" but the terminology is the same.
May not be the prop and I would be first looking at the
- motor height on the transom and the relation of that "plate" to the bottom of the hull proper
- review the trim angle in relation to the speed when this happens in a turn. When the motor is trimmed out the prop is closer to the surface and more chance of getting aired.
- as well as the design of the hull especially the keel line. If this is on something like an alloy with a keel section that gets tapered towards the stern then that can cause problems in a turn as it can create turbulance and aerated water around the prop.
13-11-2001, 03:51 PM
Sounds like he's mounted the motor a tad high mate. Did the yammy cavitate? I don't think the edgecracker has a keel down the centre, but if it does it may be too long. It may need to be shortened off a bit. Have you plyed with trim angles, it may just be jacked out too far. If you can't figure it out, take it back to your friendly local dealer, and get him to swap the hull for a Hornet. ::)
15-11-2001, 04:31 PM
Tested it thouroughly again with the experts,they reckon the pro has had a patch up adn it lost its cup???and then they agreed the prop was to big..We played with all trim possibilities still cavatates or ventalates
Rasser you are correct for a change!!! there is no keel down the guts,but the prop is the problem,the length is the same as the yammy but the merc weighs 45 kgs more so you would think the motor would be well and truly in the water but still the slightest pull on the tiller and its just sits and revs on the spot basically...
Who knows getting a new prop we are testing Friday again..
another silly question should a 25 hp 2 stroke go the same full speed as a 25 4 stroke??????l know the answer just curious as to what others think.They are the two motors l'm testing by the way.
15-11-2001, 05:54 PM
I recon the 2 stroke will jump out better & possibly have a bit more top end due to the extra weight of the 4.
It will also depend on the props, gear box etc etc. Alot of variables.
26-11-2001, 08:54 AM
queensland fishing mouthly did a test of the 40 hp 2 stroke & 4 stroke. the results was that there's not a lot between them . they tested em on two boats set up the same and noise was the only main difference be waiting for your results .
27-11-2001, 05:22 PM
Would a cav plate help??
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