1967 16-footer, Engine Mounting Height

Optimizing the performance of Boston Whaler boats
mikehansen
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1967 16-footer, Engine Mounting Height

Postby mikehansen » Sat Feb 11, 2017 8:32 pm

I got [a 1967 Boston Whaler 16-footer] from a Government auction. It was totally trashed and I have completely restored it.

I am ready to install [a 2001 Evinrude 50-HP four-stroke-power-cycle outboard engine]. The holes in the transom indicate that [the previously] mounted engine was installed as high as possible in order to get the [lower engine mounting] bolts in the splashwell. By doing that, the [Anti-Ventilation] plate will be about 4-inches above the keel. From what I have read the A-V plate should be roughly even with the keel or not more than 1-inch above or below. If I mount the engine lower, the bottom bolts will be into no-man's-land of the hull. What is the solution to my problem? HELP. Thanks.

Jefecinco
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Re: 1967 16-footer, Engine Mounting Height

Postby Jefecinco » Sun Feb 12, 2017 10:20 am

Before going to a lot of possibly unnecessary worrying about it try out the lightly elevated position available.
Butch

jimh
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Re: 1967 16-footer, Engine Mounting Height

Postby jimh » Sun Feb 12, 2017 10:30 am

See the FAQ on this topic. The FAQ has a lengthy and detailed answer on precisely your question:

http://continuouswave.com/whaler/reference/FAQ/#Q8

If the lower transom engine mount holes clear the bottom of the splashwell, that is good. In order to offer cogent advice, more information from you is needed:

--What is the distance between the upper and lower holes?

--What is the distance between the upper holes and the top of the transom?

Please reply with the requested measurements.

ASIDE: the first Boston Whaler boat to be designated as a MONTAUK was made in c.1973. There were no c.1967 Boston Whaler boats with the model designator MONTAUK.

ASIDE: a boat that has been in government service since 1967 would, by definition, have to be "totally trashed." Egads, it seems incredible the government hung on to that boat for 50-years. They dispose of perfectly good ten-year-old welded aluminum S.A.F.E boats these days.

mikehansen
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Re: 1967 16-footer, Engine Mounting Height

Postby mikehansen » Tue Feb 14, 2017 8:42 pm

The upper holes are 2" below the transom and the top to bottom is 6" center to center. The boat was a Currituck originally and I have installed a Specialty Marine center console and a Newport seat.

jimh
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Re: 1967 16-footer, Engine Mounting Height

Postby jimh » Tue Feb 14, 2017 11:26 pm

MIKE' replies with the information I solicited:

The upper holes are 2" below the transom...


That is close to perfect. See the FAQ:

The holes in the transom should be 1 and 7/8-inch below the top of the transom. In no case should they be closer than 1 and 3/4-inch to the top of the transom.


The spacing of the top holes to the top of the transom on your boat sounds okay. The engine mounting bracket will probably be resting on the top of the transom if the holes are 2-inches below.

...the top to bottom is 6" center to center.


That is a very odd measurement. The spacing of the holes should be either 8-inches (normal), 7.25-inch (one-hole up), or 6.5-inches (two-holes up). With a spacing of 6.00-inch between top and bottom holes the mounting bracket of the engine will be an interference fit. Maybe you measured on the inboard face of the transom. Maybe on the outboard face of the transom the holes are on 6.5-inch center and match the engine mount, but have been drilled with a slightly upward angle so they came out in the splash well with only 6.00-inch spacing.

My inference from these measurements is that your engine must be installed with the engine mounting height set at a minimum of two-holes-up or 1.5-inch higher than the lowest possible setting.

Having the engine mounted two-holes-up is not a particularly troubling situation. Many people find that mounting two-holes-up and using a modern propeller with some aggressive blade cupping works very well.

Note that this mounting height is not "as high as possible" as you initially described. The engine could be mounted another hole-up or 0.75-inch higher. That would be a three-holes-up mounting. That may be too high unless you have a very unusual propeller.

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Phil T
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Re: 1967 16-footer, Engine Mounting Height

Postby Phil T » Fri Feb 17, 2017 12:24 pm

Many Boston Whaler owners have reported that the recommended mounting height for an E-TEC is the highest or 1-down from the highest bolt hole position.

This is assuming you are using a high quality stainless steel 3 bladed prop.

To avoid using the blind holes and to accommodate the shallow splashwell, the recommendation is for the lower set of holes to be either 6 1/2 or 7 1/4 below the top holes. NOTE: Measurements are center to center.

Using the 6 1/2" spacing will allow you to raise your motor all the up.
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