1970 NAUSET 16 Re-power

[Crabbydick]

I have a 1970 NAUSET 16. I plan to re-power with either a Suzuki 90 or Yamaha F70. [I have thought of re-powering] maybe [with] a Suzuki 75-HP engine if 90-HP is too much.

Q1: What are the pros and cons of [a SUZUKI 75, a SUZUKI 90, and a YAMAHA F70] on [A 1970 NAUSET 16] boat in terms:

• of weight on an old but solid transom
• boat speed [at full throttle]
• miles-per-gallon fuel economy[at best crusing speed]
• price
• or [in term of] anything [you think is] important?

[Phil T]

This topic has been covered extensively. Use the site search feature.

[jimh]

Rather than impose on readers the burden of looking up and researching the actual data for the several criteria you propose to be compared between the two engines, you should give readers the data that you have already collected about them, such as the WEIGHT of each engine and the ACTUAL DEALER QUOTED COST of each engine.

To expect readers to undertake research about the engines you are asking about for basic characteristics of these engines like their weight and cost is not a reasonable burden to place on the readers. If you are actually serious about buying either engine, you should be collecting all of this data yourself.

About all I can say at the moment about WEIGHT and COST is:

For COST, lower is better, but you must compare at the same power rating.
For WEIGHT, lower is better, but you must compare at the same power rating.

If you want to compare disparate power ratings, you can divide the COST and the WEIGHT by the POWER to get new data, like

COST per HP
WEIGHT per HP

But I don't think those scaled ratios will be particularly useful.

As PHIL T mentions, I suspect that if you employ the search function you will find many prior discussions about re-powering 16-foot hulls with various brands of engine at various horsepower ratings.

Regarding choice of a brand, I recommend you visit the actual dealer selling a particular brand, and assess that dealer, his business, his shop, his experience in installing new engines on 54-year-old boats, his actual interest in selling a loose motor to you and installing it on your boat, and how comfortable you feel about handing that guy a check for $8,000 to $11,000, having him as your spokesperson for getting any factory warranty support, and using his shop for future routine maintenance, and how accessible the location is relative to where you will be keeping the boat.

[Crabbydick]

All I really need to know:

Q2: is the 344-lbs dry weight of the Suzuki 90 too much [for a 54-year-old NAUSET 16] boat?

[jimh]

Q2: is the 344-lbs dry weight of the Suzuki 90 too much [for a 54-year-old NAUSET 16] boat?

You can determine this yourself using your boat and the engine that is already on the transom of you boat. The method is easy:

Find the actual weight of the engine on the transom of your boat now. For example, let us say the weight on the boat now is 225-lbs.

Then subtract this number from 344-lbs. For the hypothetical weight of 225-lbs, the difference is 334 - 224 = 119-lbs.

Now add 119-lbs to the transom on your 54-year-old boat using sand bags or lead weight, or other dense objects so the weight is concentrated at the transom.

With the new total weight of 334-lbs on the transom, observe the position of the engine splash well drains relative to the static water line.

If the engine splash well drains are submerged below the static water line, then the 334-lbs transom weight is too much.

Conduct this experiment and report the outcome.

Also, the general principle involved here is that the strength of the transom of the 54-year-old NAUSET 16 boat has not been INCREASING with age.

A reasonable inference can be made by looking at the original maximum power rating for the boat, and then finding the weight of a typical 1970 engine of that horsepower. You should be able to find the maximum power rating of your boat on its capacity sticker. Typically that rating would be either 80 or 100-HP.

Then look at the weight of an engine of that horsepower that was manufactured in 1970. You can find the weight of older two-stroke-power-cycle engines in a survey in the article

Weight of Older Outboard Engines
https://continuouswave.com/ubb/Forum3/HTML/011042.html

For example, from that survey article, you would find the following historical information:

OMC V4 1632 cc platform, 85/88/90/100/115 HP
20 inch shaft, elec. start, man. tilt -- 288 lbs
20 inch shaft, elec. start, trim/tilt -- 301 lbs
25 inch shaft, elec. start, trim/tilt -- 311 lbs

From that list, the most appropriate engine seems like the 301-lbs models.

Now you can make an inference about the weight of the engine that would have been available in c.1970 that had 80 to 100-HP and could have been used to power a NAUSET 16: about 301-lbs.

From that, you have to decide if after 54-years of use, can the hull accommodate an engine that weighs 344-lbs or 43-lbs more.

Who better than you do decide this for your boat and your plan to buy a 344-lbs engine?

So the decision is really up to you. Exactly who else are you willing to delegate to in order to decide?

ASIDE: I recommend you read this article regarding powering older 16-foot hulls and the engine weight that is appropriate:

Storm Story: July 17, 2006, Manitoulin Island
https://continuouswave.com/ubb/Forum1/HTML/013113.html