Zodiac Mark III Futura - Correct Motor Height

[ZodiacTiller]

Mea Culpa: I've read all the proper height posts in the forum, but still have questions:

So, I got the Mark III with the new Yamaha F25 EFI four stroke. I mounted the motor flush to the top of the transom and the Anti-Cavitation plate sits a good few inches below the keel....but more or less inline with the bottom of the speed tubes. Most things I've read say the AC plate should be inline with the keel...?1".

1) Is it correct to have the AC plate near the bottom of the speed tubes where, theoretically, you'll be planing (see photo i've linked to below)?

2a) If not, where would you try and position the AC plate relative to either the keel or speed tubes?

2b) If you don't plan on being WOT every moment and, instead, are pulling kids on tubes and stuff, does that change the equation?

3) If #2 above requires raising the motor, what method is best to do so? I was thinking about drilling like 4 holes about 3" in depth in the transom and installing threaded sleeves into which I could insert threaded screws through the extension block with washers to clamp the extension piece from above. I'd like to avoid epoxying the extension piece as I'm thinking the height adjustment will likely be a longer-term trial and error ordeal....

Thanks for any insight....

http://www.zodiac-boats.co.uk/acatal...ii-2010-11.jpg

 

[Sea Rider]

Correct motor height is relative, there are boaters that likes for water flow to pass at speed right above AV plate, others between AV plate and splash plate, others like me right under splash plate. All 3 positions will give different prop thrust.

Which type of problem is combo experiencing ? With trim set to neutral (90?) and a boater sitting up front, go for a wot spin on flat calm no wind water cond and check if with back/over transom water splashes on straight water courses, then perform close tight close turns at speed and check if with prop aeration, report your findings..

PD : Sib must have all their air chambers fully inflated to factory specs, in this type of Sib, speed tubes fully supports Sib while on plane.

Happy Boating

 

[ZodiacTiller]

Thank you for the response. It sounds like the OB is in the general range (between the AV and splash plates), but that wasn't at WOT....it was at just above planing speed and it felt a little laggy.....I have a few more break in hours before WOT, so I'll resurrect this thread when I'm able to do so....appreciate the feedback..

 

[Sea Rider]

There isn't much difference between an inflatable boat that rides on plane at less throttle and at max wot rpm, water flow usually passes at same lower leg height when AV plate rides parallel to water level and Sib rides with well distributed load on deck. Being a tiller OB report your findings once break in period has ended, pull head over transom and visually check at which lower leg height is water flow passing by at wot.

Happy Boating