115 Mercury props

Alan Mckewan · 08 September 2001, 23:28

I am about to fit a 115 Merc 2-stroke onto a 5.5 Humber. The engine was previously fitted on a much bigger, heavier rib, and came with a laser prop which I think might be too small. Any suggestions what prop pitch I should use?

sasa · 08 September 2001, 23:44

Hi Alan,

I have a Mercury 90 fitted on my Viking 540. Recently I bought a Laser II prop and it is much better than the standard-fitted Black Max. The Laser II is 13 1/4 x 20 inch (diameter x pitch) and is just about perfect for my boat.

What are the dimensions of the Laser prop?

Giving that your engine is more powerful and assuming that your Humber weighs more-less the same as my Viking, you'll probably need a 22" or 24" pitch.

Hope this helps!

Sasa

Alan Mckewan · 09 September 2001, 08:31

Thanks for the help, My laser 2 is also 20 inch pitch. I will give it a try but it almost certainly too small unless the gear ratio is different between the 90 and the 115. I will have to contact Steel Developments Ltd. to get it re-pitched.

batfalcon · 10 September 2001, 06:33

I remind to you all that there is a thread some days ago for an Al prop exchange.

Michael