1987 MONTAUK 17 with Yamaha F70

Optimizing the performance of Boston Whaler boats
TexasOutrage
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1987 MONTAUK 17 with Yamaha F70

Postby TexasOutrage » Thu Jun 02, 2022 11:30 pm

Recommend a specific brand, model, and pitch stainless steel propeller for a Yamaha F70 on a 1987 MONTAUK 17.

jimh
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Re: 1987 MONTAUK 17 with Yamaha F70

Postby jimh » Fri Jun 03, 2022 8:50 am

If you give some additional information, readers can give you better answers:

Q1: what is the total boat weight on the water and ready to go?

Q2: what is the engine gear ratio for the F70?

Q3: what is the manufacturer's recommended optimum engine speed range for full-throttle for the F70?

TexasOutrage
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Re: 1987 MONTAUK 17 with Yamaha F70

Postby TexasOutrage » Fri Jun 03, 2022 10:54 am

I do not know total weight of boat. It is a 1987 17’ Montauk with a 22 gallon fuel tank. Motor has not been installed yet.

I was hoping someone on this forum had already repowered a classic Montauk with a Yamaha F70 and could give me feedback on their propeller selection process. My dealer will do water trials after installation and will test various propellers.

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Phil T
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Re: 1987 MONTAUK 17 with Yamaha F70

Postby Phil T » Fri Jun 03, 2022 11:14 am

There have been dozens of owners who have re-powered a Montauk 17 with an F70.

Through their testing, here are owner tested and recommended propellers:

13 x 17 Yamaha Painted SS
13.25 x 14 Yamaha Performance Series (Talon)
13.25 x 14 Power Tech SCP

Performance results should be taken after break-in has been fully completed.

* Note size is specific to the make/model listed only. Engine should be mounted two-holes up.

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1992 Outrage 17
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jimh
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Re: 1987 MONTAUK 17 with Yamaha F70

Postby jimh » Fri Jun 03, 2022 11:20 am

You can find this topic discussed in the archives. For example

Montauk 17 Yamaha F70 Propeller
https://www.continuouswave.com/forum/vi ... php?t=4505

MONTAUK 17 Re-power with Yamaha F70
https://continuouswave.com/ubb/Forum4/HTML/008227.html

Information about the engine gear ratio and the engine manufacturer's recommended engine speed range at full throttle will be necessary for you to evaluate the sea trial results of testing any propeller.

Total boat weight is needed to assess if the propeller and engine are working effectively to move the boat at the specified boat weight.

On small boats, any change in boat weight has an impact on performance because the total weight is generally not very much, perhaps less than 2,000-lbs. Adding one extra 200-lbs person means a ten-percent increase in total boat weight. The effect of more weight in the boat adds up rapidly to decreased performance. For a boat with one person or a boat with four persons there will be a difference in the optimum propeller.

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Phil T
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Re: 1987 MONTAUK 17 with Yamaha F70

Postby Phil T » Fri Jun 03, 2022 11:26 am

Yes.

I believe the search engine feature of this site would be an appropriate tool to provide that information.
https://continuouswave.com/whaler/search.html

Using the keywords "Montauk" "Yamaha" "F70" "prop" and "size" would be suggested.

Here is one such thread:

https://continuouswave.com/ubb/Forum4/HTML/007793.html
1992 Outrage 17
2019 E-TEC 90
2018 LoadRite 18280096VT
Member since 2003

TexasOutrage
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Re: 1987 MONTAUK 17 with Yamaha F70

Postby TexasOutrage » Fri Jun 03, 2022 2:39 pm

Thanks. I will review the information in these links.