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[Easyroller73]

FSRV must use a submerged propeller apparently but how is this determined, stationary or on the plane?
If its on the plane how do you race a monohull with surface drive or don't you?

[w3bby]

FSR-V is a submerged drive i.e. under the hull, surface drive is out of the transom and is raced as FSR-O.
Within Naviga you race FSR-V with submerged drive around an M course counterclockwise and FSR-O with surface drive around an oval course clockwise.

[Easyroller73]

Thanks so the submerged drive is a nice straightforward definition. A propeller under the hull and in front of the transom rather than just underwater water, so an equivalent to an outdrive would be cause for head scratching for the equivalent of a scrutineer?
I suspected this as I noticed somewhere else the suggestion that surface drives etc were just an excuse to show off fancy metalwork!
I am just querying as I am resurrecting an ancient hull - early Ripmax, Contestor (late 60's vintage - I bought it whilst a student and graduated in 1971 - I think and whilst filling my previous butchery to sort out what to do started wondering about playing with two concepts, near surface drive and air cooled engines.
I have a number of 0.21 buggy engines, well run in, and guess a model boat at speed will be as fast as a 1/8 scale Stock Car was - their previous home.

[Easyroller73]

Now specifically about the air cooled motors, if I was to install two devices analagous to the old self bailers we used on racing dinghys around the point the tube goes through the hull to open say an eigth of an inch is this still an underwater drive?

[w3bby]

Surface drive is essentially the faster of the two as only about half of the propeller is in the water (less drag). It is also generally less nimble in handling.

A earlier mono-hull type boat may well struggle with a surface drive as the hull is not designed for beneficial use of the system.

Not sure what you mean in your second part, do you have the possibility to load a sketch of your idea?

[Easyroller73]

I'll try to add pictures,that's the prototype but if set to open to maybe no more than a few millimetres it should provide a good venturi both to self bail the engine bay and to entrain air to the centre section of the hull which combined with exhausting into the same area would achieve a similar effect to surface mounting the prop.
As for your comments about the hull, it is a biconcave fully straked V hull which I have no doubt will never prove earth shattering but I have had for nearly 40 years and can be copied to provide a cheap experimental vehicle. Sorry about the quality of the photograph and my apologies to the moderator this message is probably far too big because I have put the images in wrongly.
Sorry - I can't add pictures, how do I add images from my computer.

[Tug-Kenny RIP]

Hi  Easyroller,

Click on  "attachments and other options"
Click on browse
Select the picture from your computer

Make sure it's smaller than 300K.  100K comes out best.
Click OK


Hope this helps

Ken

[Martin (Admin)]

 
Also see: http://www.modelboatmayhem.co.uk/forum/index.php/topic,23.msg452964.html#msg452964

[Easyroller73]

Thanks Ken, I will follow your instructions and hope to be surprised, the self bailer is easiest, a chute which opens through the hull and relies on venturi effect to drain the hull at dinghy planing speeds,to save web space that is a lift from another site - offering them for sale so unlikely to be copyrighted.
The hull I am planning to use is I hope added as an attachment but I would agree it is unlikely to be very agile.