1988 SUPER SPORT LIMITED 17 Re-power

Optimizing the performance of Boston Whaler boats
wandererr1
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Joined: Fri Aug 26, 2022 7:45 pm

1988 SUPER SPORT LIMITED 17 Re-power

Postby wandererr1 » Fri Aug 26, 2022 7:55 pm

[To repower my 1988 SUPER SPORT LIMITED 17 boat] I have bought a 2022 TOHATSU 90-HP four-stroke-power-cycle engine. I have not bought a propeller.

Give me advice on a propeller.

Engine Type: Tohatsu MFS90AETL Four Stroke
Horsepower: 90
Cylinders: 4
Shaft Length: 20-inches
Steering: Remote mechanical
Starter: Electric
Weight: 392-lbs
Full Throttle Range: 5000 to 6000 RPM
Displacement: 1995 cc
Induction System: EFI
Gear Case 2.08:1

jimh
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Location: Michigan, Lower Peninsula
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Re: 1988 SUPER SPORT LIMITED 17 Re-power

Postby jimh » Sat Aug 27, 2022 8:58 am

If you think the boat has a speed potential of 40-MPH, use a 16-pitch propeller.

A better recommendation can be given if you answer these questions:

Q1: What was the top boat speed for the 1988 SUPER SPORT LIMITED 17 with its previous engine?

Q2: What was the horsepower of the previous engine?

wandererr1
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Re: 1988 SUPER SPORT LIMITED 17 Re-power

Postby wandererr1 » Sat Aug 27, 2022 10:24 am

Thanks for the reply Jim.

Previous motor was a 1988 Johnson V4 90 HP. Boat would run 38-39 mph on GPS with two people (350lbs) and about 10 gallons of fuel

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Phil T
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Location: Was Maine. Temporarily Kentucky

Re: 1988 SUPER SPORT LIMITED 17 Re-power

Postby Phil T » Sat Aug 27, 2022 12:09 pm

Owner recommendations for this Whaler model/outboard combination include:

Ballistic 13.5x17 Stainless
Mercury Vengance 13x17 (Hub kit - 835284Q 1)

*Note size only applies to the specific prop model listed and engine is mounted 2-holes up, with the top bolt in the 3rd hole down from the top.
1992 Outrage 17
2019 E-TEC 90
2018 LoadRite 18280096VT
Member since 2003

wandererr1
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Re: 1988 SUPER SPORT LIMITED 17 Re-power

Postby wandererr1 » Sat Aug 27, 2022 1:10 pm

Thank you Phil.

jimh
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Re: 1988 SUPER SPORT LIMITED 17 Re-power

Postby jimh » Sat Aug 27, 2022 3:06 pm

Assuming the engine can accelerate to 5,500-RPM with a 17-pitch propeller, a boat speed of 38 to 39-MPH (which is statute miles not nautical miles) looks quite reasonable, assuming the propeller SLIP is less than 10-percent.

My PROPELLER CALCULATOR can help you assess propeller selection when working in statute miles dimensions.

If you prefer to work in nautical miles use the alternate calculator.

wandererr1
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Re: 1988 SUPER SPORT LIMITED 17 Re-power

Postby wandererr1 » Sat Oct 01, 2022 12:23 pm

Since I now have more than ten hours run time on the Tohatsu 90 HP engine, that allows me to get in some short full throttle runs. Here is one data point:

At full-throttle the TOHATSU 90-HP engine accelerated to 5,600-RPM, and the boat speed was then 41-MPH. There were runs on two directions with this outcome.

For this performance data, aboard the boat were me (245-lbs), a dog (40-lbs), 16-gallons of fuel (100-lbs), and a battery (50-lbs)

The 1988 SUPER SPORT LIMITED 17 with TOHATSU 90-HP engine sits in static trim a little low by the stern. In the future I will move the fuel tank and the battery forward to be underneath the front seat.

Sea condition were a light chop with a 10-knot breeze on the beam.

My impression of the boat performance with the SOLAS 13.2 x 19-pitch aluminum propeller was good.

Acceleration at full-throttle from a standing start was excellent. The bow rise was very little. The hull trims-out nicely..

The engine mounting height is three-holes-up from lowest possible.

The TOHATSU 90-HP has a working maximum engine speed between 5,000 and 6,000-RPM. Maximum engine speed is 6,300-RPM.

I plan to buy and test a stainless steel propeller.

I want to squeeze-out all the boat speed I can from the TOHATSU 90.

When I have more data available I will append the data to this thread

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Phil T
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Re: 1988 SUPER SPORT LIMITED 17 Re-power

Postby Phil T » Sat Oct 01, 2022 12:37 pm

Did you forget the recommendations already posted for you?
1992 Outrage 17
2019 E-TEC 90
2018 LoadRite 18280096VT
Member since 2003

wandererr1
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Re: 1988 SUPER SPORT LIMITED 17 Re-power

Postby wandererr1 » Sat Oct 01, 2022 1:26 pm

No Phil, I remember. I am still doing my on own testing and collecting data