Cavitation plate

Power Boats only. Please include the boat type in your question.
Edd
Active Poster
Active Poster
Posts: 204
Joined: Wed Oct 11, 2017 11:19 pm
Location: Georgia

Cavitation plate

Post by Edd »

Is there a consensus on how far below the hull the cavitation plate should be on a boat like the lm18 or fs18? I’m trying to fine tune my lm18 .

fallguy1000
* Bateau Builder - Expert *
* Bateau Builder - Expert *
Posts: 10198
Joined: Tue Jan 12, 2010 12:25 am

Re: Cavitation plate

Post by fallguy1000 »

In plane of hull bottom and even. If it comes out on turns; lower it. If it makes a deep vee in the water raise it.
My boat build is here -------->

viewtopic.php?f=12&t=62495

TomW1
Very Active Poster
Very Active Poster
Posts: 5844
Joined: Sun Apr 19, 2015 10:57 pm
Location: Bryson City, NC

Re: Cavitation plate

Post by TomW1 »

Man I missed this back when you asked it. Normally the Cav plate shoul should be even with the bottom of the hull +/- 1/2". Too low and you're lugging the motor by having to push to mush water with the motor shaft, to high and you create ventilation making the prop ineffective. This is especially important for the FS and LM as they are shallow water boats.

Tom
Restored Mirror Dinghy, Bought OD18 built by CL, Westlawn School of Yacht Design courses. LT US Navy 1970-1978

Cbuf
Active Poster
Active Poster
Posts: 356
Joined: Sat Mar 30, 2019 10:38 pm
Location: Wisconsin

Re: Cavitation plate

Post by Cbuf »

Aim for higher that you think, but I built heavy. I get you some pics of mine when I get a chance. I still want to go up a hole or 2 and test it out.
See my LM 18 build here.
viewtopic.php?t=64254
See my LM 18 Questions here.
viewtopic.php?f=2&t=64299&hilit=lm18\
Finished Boat Here
viewtopic.php?f=25&t=65173

Edd
Active Poster
Active Poster
Posts: 204
Joined: Wed Oct 11, 2017 11:19 pm
Location: Georgia

Re: Cavitation plate

Post by Edd »

Follow up, After a couple trips with the plate even to 1/2 in above the hull, I dropped it back to about an inch below where it originally was. With it up the boat was a little squirrelly, and sluggish. I still have the stock prop though. Also I didn’t gain anything. So apparently the sweet spot was where it was.

Post Reply

Who is online

Users browsing this forum: No registered users and 10 guests