Shafts thru the transom?

That's the setup of Sonny Miller's drives. They are called CAL500.

 

There are many non-trimmable surface drives available. I think the ones Trouty pictured are Seafury, designed if I recall correctly by Renato Levi.
But the point you made earlier still stands Gonzo - the cost of props alone rules surface drives out if you're after a cheap propulsion system. And to develop one from scratch I would expect to be hellishly expensive....

 

Hi guys, I'm new to this board, I've chased a thread over from OSO. I must say, it's refreshing to get 'out for a walk', talk with some new people, here different opinions etc.

This thread is very interesting because I have a 30' Corsa hull that needs complete refurbishing and was tossing around the idea of building a surface drive system for it. Carry on fellas...

Sincerely,
Brian Kamrath

 

OSO ?....

 

Oh sorry, OSO= Offshore Only

Brian Kamrath

 

beautiful boat!

 

Thanks! It was said to have a Kevlar layup. The beam is 7' so when finished should be a really quick ride. My 25' Martini is also 7' wide ( measured at the widest part) 6' at the wetted area of the transom. It knifes through waves quite easily. Ooops, I'm rambling on someone else's thread!, back to work I go!

Brian

 

My boat is set up just the way your asking, a straightshaft through the transom and a surface prop and rudder. There are some issues setting it up. The distance betweenthe coupling and the cutlas bearing will probably be long, so you will have to use a larger shaft diameter to eliminate vibration, the stuffing box will be out of the water when on a plain so you'll have to use a dripless, or supply the packing with water to cool it (an easy fix) I am running a Elis elephant ear 3 blade prop behind a 330hp engine giving my 27' a crusing speed of aprox 30knots at 3000rpm.

 

Buck I applaud your thinking "outside the box" I am a great believer in alturnitive drive systems and surface peircing is the way to go for speed and economy.

Take a look at Symplicity Drive it's a symple bolt on application.

By the way what type of vessel are you thinking of? Lenght , HP, and useage?

 

How about getting up on plane compared to an outdrive? Less than thirty knots is not better than what an outdrive will get.

 

The only thing different about getting up on a plane with my boat is the engine rpms jump for a few seconds (5 -10) as the prop transitions from fully submerged to surfacing piercing. But she comes ot of the hole as fast as my other boats.

I'm getting a better then 30k at 3000 RPM cruise with the same prop I had with the tired 260hp engine. I need to reprop and I'm sure I'll pick up at least 5 knots now that I've got the new 330hp engine. The $800.- $900.. just was'nt in the budget this year.

 

CaptPPan' where can I see the Symplicity Drive.
Thanks for the info

 

What was the speed with the tired 260 HP?

 

The speed was about the same at 3000RPM, I don't like to push my motors much above that. I figure with the bigger engine I can push a bigger prop, jmore speed same RPM. She tops out now at around 42knots.


http://www.simplicity-marine.com/smd1.htm

 

Looks like this

More Pictures on "pourposing" thred