prop clearence

[fire-engine]

Question, How much clearence btwn prop and antiventilation plate? Right now I have 3/8 in, I was told to run larger dia. I'm running 13 1/4x18 on a 21'shallowsport quahedraul w/tunnel hull. evinrude 1988 120 hp, was also told to close off top holes of water pickup any comments would help. also rpms are 5900.

 

[Dhadley]

Re: prop clearence

As a "rule-of-thumb" you need about that. You might get by with a bit less -- depends on the prop. Some flex more than others.<br /><br />Yes, its not uncommon to close off the top two. We do it by tapping and screwing in a plug. There is also room to create another inlet hole below the lowest one. There are scoops you can install (from Evin/John) that work really well too.<br /><br />One of the larger cav plate fins that start at the front of the gearcase will help increase water pressure too.<br /><br />Good luck!

 

[fire-engine]

Re: prop clearence

Dhadley, thanks, am running one of the largest compression plates i've seen 30" aluminum with downward thrust. thanks again for the reply.