1967 13-footer with 50-HP

Optimizing the performance of Boston Whaler boats
Posts: 1
Joined: Mon Sep 26, 2022 6:00 pm

1967 13-footer with 50-HP

Postby rocketwhaler1 » Mon Sep 26, 2022 6:12 pm

I have a 1967 13-footer. The transom has been modified to work with a long shaft outboard.

The engine Is a 2011 Tohatsu 50 TLDI. I have not been underway with this boat as of yet. The propeller on the boat now appears unsuitable: it is huge and intended for heavy loads.

Recommend a propeller for this boat-engine combination.


Posts: 10790
Joined: Fri Oct 09, 2015 12:25 pm
Location: Michigan, Lower Peninsula

Re: 1967 13-footer with 50-HP

Postby jimh » Tue Sep 27, 2022 8:17 am

Answer the following questions:

Q1: what is the engine gear ratio?

Q2: what is the manufacturer’s recommeded full-throttle engine speed range for optimum performance?

Q3: what is the brand, number of blades, material, model designation, diameter, and pitch of the current propeller?

Q4: how will you measure engine speed?

Q5: how will you measure boat speed?

Q6: what will be the typical total weight of the boat during normal operation?

Q7: what is the engine mounting height? Describe engine mounting height by the number of hole above lowest possible position as detailed in the pinned article at the top of this forum:

Engine Mounting Height Nomenclature
https://continuouswave.com/forum/viewto ... ?f=7&t=739

Conduct on-the-water testing using the existing propeller as described at

Propeller Testing: Evaluating the Data Obtained
https://continuouswave.com/forum/viewto ... f=7&t=7196

and report all the data mentioned in that article.