twin outboards on deep vhull advice

[Old School]

This shows a dual Proboat layout on a 900 mm hull. Later testing showed the props to be about 10 mm too low. Once adjusted upwards the boat planed well with no ill effects. The builder has several videos of the boat.

https://www.youtube.com/watch?v=XrQXuAVtED4&list=PLD-pvcRhRL1iZpVhK9TPIdIm1fF5q9sAT

Outboard adjustment on the prototype

https://www.youtube.com/watch?v=B-NbRae8iw0

[RaisedByWolves]

Yeah, what I'm thinking is that the center of the forward edge of the anti cav plate should be inline with the bottom of the hull where ever where each engine sits.

Ie if the motor is centered, the cav plate is at the level of the bottom most point of the V. If offset to the side they will need to be raised to accomodate the rise of the rear of the transom.

[JestDanny]

sub surface drive vs surface drive? I just noticed something with these outboards, on all the other outboard lowers K&B, Lawless, ect, they have a very large cavitation plate, made to run high-performance surface drive?(yes) These little HK outboards have no real cavitation plate, are they made should they be run sub-surface? Also the nitro lowers have a large deep skeg and run larger race props again pointing to surface drive, with the HK 's much smaller skeg and props is this pointing to sub-surface drive? Those HK outboards originally come on the H2O style tunnel, any body got one? Is it set up as surface or not?

[MadProps]

these outboards are surface running setups and I have experience setting up surface run race motors I just never have mounted surface run race motors on a DEEP V.... so this is what presents new challenges and questions for me

I set my twins so the prop shaft is even with hull bottom and have a ton of adjustment to move upwards for performance which I believe they will need to be raised higher still & they really cant be lowered much more anyways
but im sure the prop shaft needs to be even with hull bottom and a wee bit higher to tune it in, its the same way I setup my real mercury race motors with same surface running gearfoot (see photos)
notice this 50's model race motor still has the cav plate although the gearfoot is set so that the prop shaft is above the hull bottom today they have done away with the cav plate on these surface running racing gearfoot with surface piercing props

if these RC outboards were real they would be setup so high that only 1 blade of the cleaver or chopper style props are in the water at a time, thats how high they are run

1z.jpg
mercury 011.jpg

I also run twin motors on my vintage Corvette runabout, now these motors are NOT race motors do not have a surface gearfoot so they are setup so the gearfoot is below the boat and the cav plate is level or slightly above the hull bottom
crosby2.jpg

[JestDanny]

So then our little 3.5cc nitro outboard lowers have no gear foot, is this the reason they have to have a large cavitation plate to run surface drive? Outboards with a gear foot then no longer need any cavitation plate for surface drive? These things you need to know.

[MadProps]

surface piercing props dont require anti cavitation plates the idea is to get them out of the water but they require low water pickups though which is an issue for speed boat setups

[boatsareus]

Mad props is 100% rite . The same rules and formula applies to the Models and works the best , Chips Outboard Service

[BigJohnnyNC]

I bought a ‘69 Mach 1 and had to hide it for 3 months until I got it painted. I knew the wife wouldn’t let me park it out front of “Her House”. I must admit it was ugly with several shades of primer on it! But it was a 428 CJ 4 speed I got for a steal! Car was straight as a arrow but needed paint & the interior looked like 2 wildcats had been having sex inside! 15 grand later I had a real looker!