More on hp ratings!!!

[bolted4]

Re: More on hp ratings!!!

I had a 12ft aluminum with evin. 9.9 thing flew. dont know elevation. If you had no shoes on you could feel the aluminum feel ready to fall apart at the rivits, but never did. Also had Starcraft 14 ft with steering console floorboards with a evin. 25hp and another with Johnny 33hp. 25hp was very nice but could have been more. 33hp was really good range for speed and felt safe but it shook the boat a little more than it should. (maybe something was out of wack but it worked so I didnt try to fix it. In the end 15hp on a 12 foot starcraft would be more than enough I believe. just my two cents. Hope it helps. <br /><br />What it everyones opinion on a 18ft bayliner semi V hull,1500lbs total weight and an 85hp? I need to get a new to me motor for it.

 

[sloopy]

Re: More on hp ratings!!!

why does the new johnson 9.9 and 15hp have the same RPM, size, weight.. etc etc?

 

[JB]

Re: More on hp ratings!!!

Sloopy: The same reason that a small block Chebby can have 195hp or 400hp.

 

[BillP]

Re: More on hp ratings!!!

Old Starcrafts are a little bigger and stronger than other mfgs of the era but I'd put money their 1972 12'r is rated for 10hp max. Those early Sears alum boats were also built sturdier than most if that gives you any indication. Back then most 14' alum skiffs were rated 15hp max. 8500' above sea level is definitey worth a few ponnies so a 15 might be the equalizer on the 12'r.

 

[alumistar]

Re: More on hp ratings!!!

after running through the worksheet, found my calculations are <br />(trans)width X (boat)length = factor<br />4.33 X 12.08 =52.3064 rounded down to 52 is on the higher end of the fifteen range. in fact the graph shows that 53 is for a 20hp, so 15 I go.....<br />to all, thanks tremendously for showing me the way to find my formulas....y'all rule!!!!

 

[sloopy]

Re: More on hp ratings!!!

The Bore and stroke are the same!!! and the prop!!!!!

 

[alumistar]

Re: More on hp ratings!!!

yeah sloopy, but where i live i found that if i get a 9.9 and change the carbeurator to a 15, then effectively i have spent the two hundred dollars that it would take to get into a fifteen anyway. i guess on the other hand, if i did do it with a 9.9 and change the carb it would be a sneaky way to get a 15 on lakes that have maximum <br />hp allowances of 10hp or less, wich is about half the lakes here.... that sounds like more fun anyway think i'll do it! thanks sloopy, that rules!