YAPQ- Yet Another Propping Question

[Bushwacker]

Originally Posted by sidelock

What is the proper mounting height for an outboard and is it the same for all v bottom boats and o/b motors ?

The correct height is whatever it takes to get the AV plate above solid water. On a 20 SeaCraft with no bracket, that typically means the AV plate, when trimmed parallel to keel, is about 1-1.5" above keel.

Zach, I agree with advice from FS and others. Motor definitely needs to come up at least 1-2 holes; need to get the height correct before screwing around with props, and also make sure your tach is accurate. Many analog tachs are often way off!

If you're falling off plane at 16 kts with that light motor and weight moved forward, the boat is trying to tell you it needs more stern lift! A 4B prop and/or a fin will give you that. And although you outweigh me by about 60 lbs, you really aren't carrying all that much gear, so your hole shot should be much better! Less pitch and more blade area will improve that! I ran my much heavier 20' Seafari with a 1975 "115" that probably wasn't much more than 100 hp at the prop, and it would plane at 12 mph with a very heavy Bahamas cruising load including a couple of coolers, 2 weeks worth of groceries, 80 gallons of gas and a couple of 170-180 lb guys and dive gear! I ran a 13 3/4 x 15 OMC 3B SST prop that turned 5400-5700 depending on load. Ken at Prop Gods can hook you up with the right prop; I'd think a 15" pitch 4B with whatever diameter is right for your 115 to wind up to it's max rated rpm would give you the performance you're looking for.

[mnwnvc]

I am running a 13 1/8 X 19 Michigan SS. I think I am happy but do not run heavy loads.
TAC only reads 5K plus but top end GPS is 41mph. Maybe it's like boats, you need more than one.

Michael