Recommend a gearbox

Hi guys -

Need your advice, as what I dont know about boats can fill tomes and tomes.

I am putting in a new engine into a 45fot (15m) Indonesian-made wooden fishing boat (the long and sleek kind - 2m wide, 1m draft).

The engine is a 4 cylinder, 4 stroke inline direct injection marine unit. Its continuous power ratings are: 42ps/1500rpm, 52.5ps/1800rpm and 57ps/2000 rpm. Compression ratio is 17.9:1.

The propeller is going to be 18-20" in diameter, no more.

I think a 2:1 gearbox would probably make the most sense, and would like to purchase a David Brown unit. For starters, are there different variants in 2:1 gearboxes from which I need to select an appropriate unit, and if so, what are the factors that will help me decide?

Second, any other suggestions on other models I should look at?

Third, anyone know where I might buy such a unit and have it shipped internationally? I need it in the Andaman Islands - so it will have to come into mainland India first.

Thanks,
VK

 

Ask on the "Metal Boat Society" also. Join http://boatdiesel.com/index.cfm?RED=WWW
There are straigt drive, Drop drive & angle drive configerations.
They are rated according to the use & length of continuious use time. Velvet drives are a dime a dozen in salvage shops, making them cheap but reliable drives.. Twin Disk has a good reputation. Some I've talked to are not fans of ZF-Hurth.
To be clear about the reduvtion you will need to size the prop size & pitch, hull speed, hull type?displacemrnt. A hard thing to juggle for a newbe. Get help from a prop shop. Worth the money, as fuel economy, engine life & boat handling depend on correct sizing. If engine is a Detroit Diesel, then it is more critical.