c.1970 SAKONNET, E-TEC 90

Optimizing the performance of Boston Whaler boats
jhomeister
Posts: 13
Joined: Mon Oct 19, 2015 9:35 am

c.1970 SAKONNET, E-TEC 90

Postby jhomeister » Wed May 03, 2017 8:14 am

I'm re-powering a 1970 Sakonnet with a 2007 E-TEC 90-HP from a Bearcat 55. I anticipate a big difference. The boat will used primarily for family cruising and to pull water skiers and tubes. I am rather unfamiliar with the E-TEC at this point. Any propeller suggestions?

jimh
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Location: Michigan, Lower Peninsula
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Re: c.1970 SAKONNET, E-TEC 90

Postby jimh » Wed May 03, 2017 8:40 am

FIrst step in propeller selection is to determine the optimum engine speed range. For an E-TEC 90, we go to my REFERENCE article. See

http://continuouswave.com/whaler/refere ... neRPM.html

For the 90-HP, we see the "Recommend Operating Range" is 4,500 to 5,500-RPM. The optimum full throttle range is a bit lower, 5,000 to 5,200-RPM.

Next we search for some previous reports on an E-TEC on a 16-foot hull.

It looks like a 17-pitch is a good starting point. Engine mounting height is also a consideration. Start at mounting the engine one-hole-up. Then we go for a test drive. Get readings on engine speed and boat speed. Does the propeller let the engine accelerate to 5,200-RPM at full throttle?

Here is a good report from the past: http://continuouswave.com/ubb/Forum4/HTML/006199.html

But the recommended STILETTO propeller may no longer be available. I think that brand was removed from the market by the actual propeller manufacturer, and you may have to look for something similar in the TURBO brand, which seems to have many similarities but with a higher retail price point.

If you can have loan of several propellers, there is no harm in trying a bunch of them. Check your local Evinrude dealer. Some Evinrude engine dealers participate in an Evinrude propeller test program, and they will loan out test propellers for sea trial on your boat.

jhomeister
Posts: 13
Joined: Mon Oct 19, 2015 9:35 am

Re: c.1970 SAKONNET, E-TEC 90

Postby jhomeister » Sat May 06, 2017 2:16 pm

Thanks Jim. As always, your thoughtful post is very helpful.

Wirenut
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Joined: Fri Oct 16, 2015 7:18 pm
Location: Ocean City,Md

Re: c.1970 SAKONNET, E-TEC 90

Postby Wirenut » Sun May 07, 2017 9:11 pm

[On a completely different topic] What are you doing with the old Bearcat?

jhomeister
Posts: 13
Joined: Mon Oct 19, 2015 9:35 am

Re: c.1970 SAKONNET, E-TEC 90

Postby jhomeister » Wed May 10, 2017 8:39 am

It has been sold, but I do have some spare parts. PM me if you are interested.