Thread subject: Whaler Central - Boston Whaler Boat Information and Photos :: Max new engine on 1976 Sport 15

Posted by Florux on 07/26/15 - 12:29 PM
#1

Hi,

I'm restoring a 1976 model 15 foot sport that has had a 60 Evinrudes since it was new. First was a 1977 60hp, and the second was a 1986-ish 60hp.
Since the boat is now getting completely restored, I am treating it with a brand new model. I'm not going to go for a fourstroke as they are generally heavier and have slower acceleration than two-strokes.
From what I can still read from the US coastgard note inside the boat it lists maximum 70 (or 75? only the 7 digit is readable) back when it was new. However, both the weights and performance from each horsepower has changed a bit in nearly 40 years.

What would you recommend for a new engine? A 75hp or 60hp engine from a weight perspective? I'd guess the current engine weighs around 100kg.

Thanks in advance for any insight!

Posted by Joe Kriz on 07/26/15 - 12:52 PM
#2

Only the 1976 model was rated for 75hp. All other 15' models after that were rated at 70hp.
http://www.whalercentral.com/userphot...lbum_id=40

However, I would not put a 75hp on that model due to weight.
If you want to stay with Evinrude, I would put the 60hp on @240 pounds
The original Evinrude 70 back in the late 1970's and 1980's weighed 248 pounds.

See our charts on engine weights here:
http://www.whalercentral.com/articles...ticle_id=4

Edited by Joe Kriz on 07/26/15 - 12:56 PM

Posted by Florux on 07/26/15 - 2:03 PM
#3

Thanks much! Think I'll go for the 60 then, even though the 75 would've been a lot of fun :-) Much appreciated!

Posted by wlagarde on 07/26/15 - 2:05 PM
#4

Also, a 70 hp motor in 1976 was rated at the flywheel (as opposed to being rated at the prop today; industry switched over ~1986). So a 70hp engine in 1976 produced ~ 60-65hp at the prop.

Posted by Florux on 07/26/15 - 2:14 PM
#5

wlagarde wrote:
Also, a 70 hp motor in 1976 was rated at the flywheel (as opposed to being rated at the prop today; industry switched over ~1986). So a 70hp engine in 1976 produced ~ 60-65hp at the prop.


That's certainly good advise. Thanks! Turns out the 60 hp engines are also significantly cheaper and will make the boat run better in the water.

Anyone got any recommendations for where to go go for advise on OMC vs Mercury vs the Japanese for engine manufacturer? I've always been fond of Evinrude for the simple reason of it being the first engine on the boat when I was a kid, but it might be a good idea to be slightly more scientific when buying a new engine...

Posted by wlagarde on 07/26/15 - 2:39 PM
#6

If you choose a new 70hp engine you would be fine too. I made the comment to make the point that any of the modern 60 or 70hp choices in the majority of cases are more than enough power.

See here for current engine choices: http://www.whalercentral.com/articles...icle_id=77

Also, Tohatsu now makes a 4 stroke 60hp option: http://www.tohatsu.com/outboards/4st_...range.html

Posted by Florux on 07/26/15 - 10:54 PM
#7

Thanks again! My concern is simply that the new 75hp engines are far heavier than the 60hp ones coming in at 320lbs vs 240, which will impact the way it floats. Going from 2 to 4 stroke will probably just add even more weight still.
As the boat appears to have been dimensioned for an engine weight of around 250lbs, maybe it's best to stick with that?

Posted by wlagarde on 07/27/15 - 4:18 AM
#8

I wouldnt go over 70 because of weight but between a 60 and 70 of the same brand motor the weight is often very similar or the same and the increase in cost marginal.

Posted by dgoodhue on 07/27/15 - 11:53 AM
#9

The only new light weight 70 is the Yamaha 4 stroke 70hp. The rest of the 70 and 75 are much heavier than 250-275 # 2 stokes that were available during production.

Posted by BlueSmoke on 07/27/15 - 12:08 PM
#10

just bought at 1977 15 sport with a honda 60 4 stroke. 239 lbs.

loving it, great match

http://marine.honda.com/outboards/motor-detail/BF60-BFP60