Page 1 of 1

Whaler Drive Power Rating

Posted: Thu Sep 06, 2018 1:27 pm
by wamair
[Note: thread moved to PERFORMANCE forum for discussion. Initial question has been rewritten to be a direct question instead of a survey asking for the number of people that knew the answer to the question—jimh]

Why [that is, for what reason or due to what element of the design] is the Revenge 20 Whaler Drive rated for more horsepower [than some other unspecified boat]?

HP or weight.

I am planning on a re-power this winter with either a 250 or 300-HP.

My 200 OceanPro at 6000-feet elevation is a little wimpy.

Re: whaler drive

Posted: Thu Sep 06, 2018 3:07 pm
by dtmackey
Loss is equal to 3% per 1000’ of elevation so a 250 would net you 214-HP and the weight of the 3.3L 200, 225 and 250 are the same in the G1 series.


Re: Whaler Drive

Posted: Thu Sep 06, 2018 3:46 pm
by jimh
Boston Whaler boats with a Whaler Drive are rated for a particular maximum power in the same way all Boston Whaler boats are rated: if 20-feet or less the horsepower rating must conform to federal regulations.

Maximum power rating is not mandatory for boats over 20-feet according to federal regulations. See the FAQ for more on power ratings.

If you are trying to ask why a Whaler Drive boat is rated for more power than a notched transom outboard version of the same hull, I can speculate: a Whaler Drive adds about 2-feet to the hull length and also substantial reserve buoyancy at the stern.

ASIDE: it has been speculated that the Whaler Drive option was created specifically for use with twin engines on the larger hulls.

ALSO: for powering a hull with an engine that exceeds the capacity plate limit, again see the FAQ:

Re: Whaler Drive Power Rating

Posted: Thu Sep 06, 2018 3:50 pm
by jimh
wamair wrote:HP or weight.

I don’t understand this comment. If you are trying to ask a question, please clarify.

Re: Whaler Drive Power Rating

Posted: Thu Sep 06, 2018 8:14 pm
by wamair
Thanks jimh . You answered my question.

I was asking if they [Boston Whaler] rated them [Boston Whaler boats] by horsepower or weight.

According to the specifications, a 1987 Revenge 20 W-T is 20' 3" long so it should be exempt from the 20' and under rule.

Re: Whaler Drive Power Rating

Posted: Fri Sep 07, 2018 7:53 am
by jimh
My understanding regarding capacity plate data is summarized in the FAQ and its linked articles.

If a manufacturer provides a capacity plate on a boat, even if the boat is not within the mandate of the federally required capacity plate, the manufacturer has established the boat’s ratings.

The capacity plate clearly establishes maximum allowed horsepower AND weight. This is easily inferred by looking at the capacity plate and seeing the data it contains.

In addition, Boston Whaler now includes a rating for maximum transom weight in their specifications for most models. For most older hulls there was no maximum transom weight rating provided. You can infer the maximum transom weight has been reached when the through-hull drains of the engine splashwell are submerged below the static waterline of the boat at normal load and trim.

Regarding your question about the method used by Boston Whaler, I already described that if the boat is less than 20-feet then the manufacturer must use the method described in the federal regulations. If the boat is longer than 20-feet the manufacturer would appear to be free to use any method they want. I have no information to share about the method being used by Boston Whaler when they are not mandated by federal regulation to use the federally required method.

Did you read the FAQ and the associated linked articles?

I think you will find they contain good information on this topic.

The Boston Whaler boat you have is identified by its federally required hull identification number. The manufacturer has issued maximum ratings for the hull for power and weight capacities. You cannot pretend these no longer exist or apply to your boat. If you wish to exceed them, you should purchase appropriate insurance against liability for any eventuality that might occur, and the insurance should explicitly state it covers the operation of the boat with power or weight that exceeds the manufacturer’s capacity plate.