1983 NEWPORT Re-power

Optimizing the performance of Boston Whaler boats
neverenough
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1983 NEWPORT Re-power

Postby neverenough » Wed Jul 17, 2019 1:08 pm

I have a 1983 Newport with a two-stroke-power-cycle outboard of 80-HP. The time for a new engine has arrived.

Can the [1983 NEWPORT 17] boat handle the added weight of a Mercury 90-HP engine that may be 70-lbs heavier than the current engine?

My other option is 60-HP Mercury.

What do you think [of these two options]?

jimh
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Re: 1983 NEWPORT Re-power

Postby jimh » Wed Jul 17, 2019 3:39 pm

What are the weights of the engines you want to re-power with?

By just describing how much more they weigh than the current engine, you don’t tell us anything about the transom weight you are planning to have with the new engines. We don’t know how much the current engine weighs.

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Phil T
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Re: 1983 NEWPORT Re-power

Postby Phil T » Wed Jul 17, 2019 6:13 pm

The Newport 17 has a max horsepower rating of 100. There were no transom weight limits or ratings back in that day.

Presuming your transom is dry and in good shape, any recreational 90-HP outboard will be acceptable. While there was a concern with Honda's 90 hp model, the BF90 has been redesigned and is now 359lbs, the same as the Mercury 90 FourStroke you are considering.

It is customary for owners completing a re-power to move some weight forward to regain a close to level trim. Many move their batteries from the stern to the console. Shifting the fuel tank to under the seat is also worth consideration

To assess the weight increase to the hull, add the additional weight amount to the splashwell area and stern temporarily in the form of water jugs, wrapped bags of cement, gravel, sand (you get the idea). Observe static trim from a distance. Operate the boat with passengers and note the hull's performance (not the engine's) coming off plane. Any water shipped over the transom?
Member since 2003
1992 Outrage 17, 1992 Evinrude 115

flymo
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Re: 1983 NEWPORT Re-power

Postby flymo » Thu Jul 18, 2019 8:38 am

If you are concerned about weight, you might consider the E-TEC 90, which is nearly 40-lbs lighter than the Mercury you are considering. Many people have re-powered that 16-foot hulls with an E-TEC 90 and have been very happy with the performance.

Alternatively, if you're willing to live with the increased weight, you might want to look at the Honda BF90 or 100, which weigh the same as the Mercury. The Suzuki DF90 falls somewhere in the middle of the weight range.

biggiefl
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Re: 1983 NEWPORT Re-power

Postby biggiefl » Thu Jul 18, 2019 12:51 pm

I had a 70 Suzuki that weighed 359-lbs on a jack plate and [the hull] handled the weight just fine. Any choice you make will be fine and yes, move the battery under the console on the port side.
On my 24th Whaler. Currently in the stable: 86 18' Outrage, 81 13' Sport(original owner), 87 11' Sport, 69 Squall. :roll:

Ghost
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Re: 1983 NEWPORT Re-power

Postby Ghost » Tue Jul 30, 2019 8:54 am

I’m adding the Evinrude E-TEC 90 to my wish list of considerations for re-power. I hadn’t really discovered that until this thread. At 320-lbs I think the E-TEC weight is only about 15-lbs heavier than the old [1971] Johnson 100 and [1983] Johnson 90 I had as a kid. Looks like a great fit.

[Nota Bene: use four digits for designating a year—jimh]

biggiefl
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Re: 1983 NEWPORT Re-power

Postby biggiefl » Tue Jul 30, 2019 1:18 pm

The E-TEC 90 is a good match especially since you currently have 80-HP. If you were replacing the OMC 90 you may not be so thrilled as the E-TEC does not have the pure brute grunt(nor thirst) of the old crossflow 90's of the day. It is only a three-cylinder compared to four-cylinder. The old Yamaha 90 two-stroke-power-cycle engine is kinda the same. Expect boat speed to be in the low 40-MPH range.
On my 24th Whaler. Currently in the stable: 86 18' Outrage, 81 13' Sport(original owner), 87 11' Sport, 69 Squall. :roll: