1970 Sakonnet Re-power

Optimizing the performance of Boston Whaler boats
Skip Berry
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Joined: Mon Aug 06, 2018 9:09 am

1970 Sakonnet Re-power

Postby Skip Berry » Sun Aug 04, 2019 7:14 am

I am working on a restoration of a 1970 Katama. I will be using a Specialty Marine Console and RPS so I guess it will be a Sakonnet now. The Katama had an 1970 Mercury 80-HP engine. I would like to replace it with a new or newer engine. I'm looking at the Evinrude E-TEC or Mercury FOURSTROKE . Both engines are heaver than the original.

I think the 1970 Mercury was about 240-lbs. The Evinrude is 320-lbs, and the Mercury is 359-lbs. The blocks for both 90 HP and 75 are the same, so there is no difference in weight between the 90 and 75 HP models of each brand.

I am looking at the Evinrude and Mercury as they are sold by a local dealer who does re-power work.

If another brand is recommended I will try to find another dealer.

Does anyone have experience or advice in this area? Thanks.

jimh
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Re: 1970 Sakonnet Re-power

Postby jimh » Sun Aug 04, 2019 10:01 am

SKIP—are you in an area of seasonal boater—a northern boater? If you are, you will love the self-winterizing of the E-TEC engine.

I am on season-11 with my E-TEC. No complaints about it from me.

Skip Berry
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Joined: Mon Aug 06, 2018 9:09 am

Re: 1970 Sakonnet Re-power

Postby Skip Berry » Sun Aug 04, 2019 4:27 pm

Thanks for the info Jim. I use the Whaler in New Hampshire, May to November.I have read about the ease of winterizing. I'm concerned with the weight. Obviously the Evinrude is lighter than the four-cycle engines.

Is 359-lbs too much for a blue 16?

How about the 320-lbs of the Evinrude?

What HP is your E-TEC and what is it on?

Tom Hemphill
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Joined: Fri Oct 16, 2015 5:04 pm

Re: 1970 Sakonnet Re-power

Postby Tom Hemphill » Sun Aug 04, 2019 6:10 pm

My 1970 (blue interior) 16-foot Whaler has a 2006 90 HP Evinrude E-TEC motor. I don't think it's too heavy but I wouldn't want anything heavier. My splash-well drains are barely above the water line at rest.

flymo
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Re: 1970 Sakonnet Re-power

Postby flymo » Sun Aug 04, 2019 9:19 pm

If weight is the primary concern, you may wish to consider the Yamaha F70. At 253 pounds it's barely heavier than your old Mercury engine, and performance will likely be about the same, as the standard for outboard power measurement has changed.

If you want to improve performance over what you currently have, go with the E-TEC 90. Many owners of both your hull and newer Montauks have installed [E-TEC 90-HP engines] with good results.

As you mention, the Mercury 90 is very heavy, and it is also huge. I have a friend with [a Mercury 90-HP] on a 170 Montauk and it looks massive--even on that boat. [A Mercury 90] would really look out of place on your classic hull.

Whatever you go with, look on this site for advice on mounting height before you get the motor installed. Most dealers will install the motor all the way down, and that results in suboptimal performance.
Last edited by flymo on Tue Aug 06, 2019 6:49 am, edited 1 time in total.

Reelescape1
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Re: 1970 Sakonnet Re-power

Postby Reelescape1 » Mon Aug 05, 2019 10:12 am

I have had a Yamaha F70 on an aluminum boat for the last three years. Fuel mileage usually is 7-MPG, and boat speed is 30 to 35-MPH with Yamaha stainless steel three-bladed 16-pitch propeller.

I'll likely re-power a Montauk with [another Yamaha F70 engine]. The hull weights [of my aluminum boat and a MONTAUK 17] are very close, so I expect similar performance.

Skip Berry
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Re: 1970 Sakonnet Re-power

Postby Skip Berry » Tue Aug 06, 2019 8:03 am

Thanks for the info. Flymo mentions the physical size of the Mercury. I never thought about that. Good point Flymo. As for the F70, my logic tells me to go for it. My "need for speed" wants the E-TEC 90.

biggiefl
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Re: 1970 Sakonnet Re-power

Postby biggiefl » Tue Aug 06, 2019 1:26 pm

Then go with the E-TEC. That much weight is not a problem. If the battery is in the stern, then [weight] is a wash once you move it.
On my 24th Whaler. Currently in the stable: 86 18' Outrage, 81 13' Sport(original owner), 87 11' Sport, 69 Squall. :roll:

Duckmanreno
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Joined: Mon May 09, 2016 3:58 pm

Re: 1970 Sakonnet Re-power

Postby Duckmanreno » Tue Aug 06, 2019 4:44 pm

I am looking hard to re-power my 1973 Montauk, and, of course, I have same concerns as [SKIP BERRY has in re-powering his 1970 SAKONNET].

I have heard good reviews on the Mercury 90 and found a good price. But the physical size of the engine is a turn off after seeing one in person. Life's decisions.

flymo
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Re: 1970 Sakonnet Re-power

Postby flymo » Wed Aug 07, 2019 6:54 am

For me, the ETEC-90 would be a no-brainer, especially with a local dealer. If they made an ETEC-100 I'd get that - you don't have to use the power all the time, but it's nice to have when you need it. With modern, fuel-injected motors, you pay no fuel penalty - look through performance reports and you'll often see a larger motor getting better mileage at cruise speed.

And sorry, Merc fans, but that 90 is a behemoth - looks like you've got a VW beetle strapped to the transom. No way.

biggiefl
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Re: 1970 Sakonnet Re-power

Postby biggiefl » Wed Aug 07, 2019 10:48 am

Since LHG left....I am not sure we have any Merc "fans" left.
On my 24th Whaler. Currently in the stable: 86 18' Outrage, 81 13' Sport(original owner), 87 11' Sport, 69 Squall. :roll: