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Author Topic:   Propping a 15 Sport with a 70 hp

Alan Hiccock posted 02-27-2002 07:13 PM ET (US)
Stock white 13 X 19 alum. is what is on the engine now, a 70 Yamaha.
Ive yet to take the boat out, any comments on this prop size for the 15 sport.
I'm about 185, 12 gal. gas, batt. most likely 900 + lbs. total weight.
Also any thoughts on weather or not cupped props or stainless steel would help me obtain max performance on this rig.
thanks for any replys,
alan

Bigshot posted 02-28-2002 11:43 AM ET (US)
try it and see. You might be fine and you might overrev. Without a tach, mute point but with a Yamagucci, you are ok right? If you are a bit high on revs a double cup will bring you down about 200.
Alan Hiccock posted 02-28-2002 01:15 PM ET (US)
Range for RPM's are 5000-6000, if I recall I'm looking for 5500 and a mild case of whiplash and i'm dialed in.
where2 posted 03-04-2002 05:04 PM ET (US)
Can't be far off, unless Yam and OMC did way different things in the lower end. My 70 OMC has a 13-1/4x19 SS with cupping. It runs 50mph WOT with my 140lbs in the boat, battery, some gas, and the bimini top down. :) MAJOR Chine-walking though! That's the scarry part.
Bigshot posted 03-04-2002 05:11 PM ET (US)
Alan....what did you find out? If you are hitting 5500 with a 19 alum. A 17"SS is where you want to be. A 19" SS will bring you down even more. I would want to be somewhere in the 5700+range personally with a light load.
Alan Hiccock posted 03-04-2002 07:40 PM ET (US)
Where 2- wow 50 mph's v cool, {I wrote down your prop size} Im v close @ 13 x 19 but no cup. Maybe worth trying am ss your size if it's good for 50.
Bigshot, still too cold here on long island boats never been out yet..
I'm considering by this weekend though if it warms up. I agree that 5700 is a good place to be slightly above the the middle [5000-6000 is my range}
Alan

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Author	Topic: Propping a 15 Sport with a 70 hp
Alan Hiccock	posted 02-27-2002 07:13 PM ET (US) Stock white 13 X 19 alum. is what is on the engine now, a 70 Yamaha. Ive yet to take the boat out, any comments on this prop size for the 15 sport. I'm about 185, 12 gal. gas, batt. most likely 900 + lbs. total weight. Also any thoughts on weather or not cupped props or stainless steel would help me obtain max performance on this rig. thanks for any replys, alan
Bigshot	posted 02-28-2002 11:43 AM ET (US) try it and see. You might be fine and you might overrev. Without a tach, mute point but with a Yamagucci, you are ok right? If you are a bit high on revs a double cup will bring you down about 200.
Alan Hiccock	posted 02-28-2002 01:15 PM ET (US) Range for RPM's are 5000-6000, if I recall I'm looking for 5500 and a mild case of whiplash and i'm dialed in.
where2	posted 03-04-2002 05:04 PM ET (US) Can't be far off, unless Yam and OMC did way different things in the lower end. My 70 OMC has a 13-1/4x19 SS with cupping. It runs 50mph WOT with my 140lbs in the boat, battery, some gas, and the bimini top down. :) MAJOR Chine-walking though! That's the scarry part.
Bigshot	posted 03-04-2002 05:11 PM ET (US) Alan....what did you find out? If you are hitting 5500 with a 19 alum. A 17"SS is where you want to be. A 19" SS will bring you down even more. I would want to be somewhere in the 5700+range personally with a light load.
Alan Hiccock	posted 03-04-2002 07:40 PM ET (US) Where 2- wow 50 mph's v cool, {I wrote down your prop size} Im v close @ 13 x 19 but no cup. Maybe worth trying am ss your size if it's good for 50. Bigshot, still too cold here on long island boats never been out yet.. I'm considering by this weekend though if it warms up. I agree that 5700 is a good place to be slightly above the the middle [5000-6000 is my range} Alan