CONTINUOUSWAVE

Q1: what is the maximum engine weight allowed for a 1996 DAUNTLESS 15?

BACKSTORY. I am about to buy a 1996 Dauntless 15 with no engine. I believe the rated maximum engine power is 75-HP, but I would like to know the maximum engine weight. I would buy a four-stroke-power-cycle engine, and perhaps a Yamaha F70 engine (because of better support in my area). But the Yamaha F70 engine weights 265-lbs (120-kg). That sounds heavy.

[Moderator's note: moved to The Gam for discussion, as the information sought is a specification for an older Boston Whaler boat.]

I cannot cite an exact date, but the practice of Boston Whaler assigning a specification to their boats that stipulated a maximum engine weight (or maximum transom weight) was not in place in 1996 (based on lack of published specification for that capacity in the printed catalogues). I believe that around c.2002 Boston Whaler began to specify transom weights for their boats. There is a thread from 2002 that lists many models and the published transom weight limits. See

Transom Weight and HP Ratings
https://continuouswave.com/ubb/Forum4/HTML/000749.html

The standard layout for a Boston Whaler catalogue is to list all the specifications on the rear cover. I have a digital copy of the 1996 Boston Whaler catalogue.

For the 1996 DAUNTLESS 15 the maximum power is 75-HP. There is no specification for maximum transom weight or maximum engine weight.

The most reasonable inference about an engine weight limit is to consider a 70-HP engine from that era. Several photographs in the catalogue show an Evinrude 70-HP two-stroke-power-cycle engine. The weight of a three-cylinder two-stroke-power-cycle 70-HP long-shaft Evinrude engine with power tilt and trim in c.1996 was about 250-lbs.

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

Regarding the rated maximum horsepower for a DAUNTLESS 15, it varied slightly, from 70-HP to 75-HP. You can see the details in my list of specifications for all Boston Whaler models in the REFERENCE section. See

https://continuouswave.com/whaler/refer ... tions.html

The DAUNTLESS 15 will be found in the section at

https://continuouswave.com/whaler/refer ... hulls11-19

With this information, I can offer the following observation.

In c.1996 the DAUNTLESS 15 model was illustrated with an engine that weighed at least 250-lbs. To re-power a 1996 DAUNTLESS 15 with an engine that weighs 265-lbs is only a 15-lbs increase over the weight of engines clearly permitted to be used by Boston Whaler.

It was typical practice to have the engine cranking battery in the stern of the boat, and a typical battery would weight at least 50-lbs. If the use of a 265-lbs engine appears to create a down-by-the-stern trim on the DAUNTLESS 15, a simple remedy would be to move the engine cranking battery forward and to be under the helm console. This should effectively remove the battery weight from the stern, and correct any undesired effect of the extra 15-lbs of engine weight.

The only negative effect of moving the battery to be farther from the engine will be the necessity of replacing the main cables that connect the battery positive and negative terminals to the engine with cables of larger wire gauge in order to reduce the resistance of those cables in order to prevent voltage drop in the cables during engine cranking from being excessive. For advice on replacement battery cables see this article:

Recommended Battery Cable Size
https://continuouswave.com/forum/viewtopic.php?t=2153

Note that for up to 10-feet, a 4-AWG cable is permitted. It is unlikely the standard engine cables will be sufficiently long to accommodate the battery being in the helm console, but since you are buying a new engine, you could include longer power cables as part of the order, and perhaps only have to pay a modest premium for the longer cables, whereas if you have to order longer cables later you will probably have to pay full retail price.

File this under the possibly useful category. Our previously owned 1999 Dauntless 16 was rated for a maximum 115 HP engine. That boat was heavy for a 16 footer.