New Motor Cavitates

[Jack380AC]

OK. So last year someone stole my perfectly good, 5HP, 2-stoke Merc. Ran like a top. Got my 9' inflatable bottom Achillies on plane and ran like a bandit.

I am testing out a new (3-4 hours) 6HP 4-stroke Merc from a friend. Motor seems to run fine but clearly does not seem to have the punch of my 2-stroke.

The real problem is that if I adjust the angle to get it to plane, the motor capitates (or otherwise just comes out of the flow of water). If I adjust it back to the normal setting, can't get her to plane. In all cases, the bow rises way more than I remember with the old motor.

My guess is that the motor is fine but what can I do to get it to give better performance. Would one of those wings help?

 

[Creekwood]

You could try lifter tabs. Here is my results. Only downside is that they make backing up the dinghy awkward.

[video=youtube;Zjhc4T7kExw]http://www.youtube.com/watch?v=Zjhc4T7kExw&feature=youtube_gdata_player[/video]

 

[moparlvr4406]

the 4 stroke just doesn't have the torque of the 2 stroke
find an older used one on craigslist

 

[Jack380AC]

I think your right. Unfortunately, I'm kinda committed to buy it. Its my next door boat slip neighbor's. If I hate it, I'll sell it next season.

 

[flyer]

Try a prop with more blade area. You may have to go custom, with the prop shop welding on some material to the edge and then grinding it down.

My 15 hp (2 stroke Johnson) on a 310 Airdeck had a cavitation/blowout problem and I went with a 4 blade prop and never looked back again.

Good Luck

 

[Jack380AC]

Well the problem did not fix itself over the winter. Go figure.

This new motor is fine for getting around but what fun is that? I need SPEED! I'll investigate props but I suspect there are no off the shelf alternatives.

Has anyone had experience with those hydrofoils? Do they even make them for such a small motor? Where Can I get them?

 

[Jack380AC]

The StingRay Junior is said to fit as small as 2 HP. Only problem is you need to drill 4 holes in the lower unit to mount.