I have just purchased my first Boston Whaler boat, a 1970 SPORT 13. This hull has several breaches of the laminate. I want to [deduce the weight of retained water in the hull] before I start restoration.
Q1: how much should a 1970 SPORT 13 weight?
Here are [weights at two configurations]:
Bare hull with all wood, steering gear, and railings removed, but with the lifting eyes at the stern and bow in place: 295-lbs.
Add the wood interior to the hull, including the anchor locker cover, two seats, the steering console and steering gear, the seat risers, and add the railings: 379.4-lbs
Q2: does this 1970 SPORT 13 hull have retained water?
Hull Weight of 1970 SPORT 13
Re: Hull Weight of 1970 SPORT 13
The weight of a 13-foot hull is reported in the REFERENCE section article on the boat. See
https://continuouswave.com/whaler/reference/13/
Weighing the boat to one-tenth of a pound is not particularly necessary. I am sure that the variation in production of the boat would easily exceed one-tenth of a pound among all production hulls.
A 1970 hull should be a hull without the bow line "smirk", and with a notched transom designed for a 15-inch-shaft-length engine. A hull like that would weight somewhere around 250 to 275-lbs.
Water weights about [8.34 -lbs] per gallon, so if your hull had two gallons of absorbed water, it will only be 17-lbs heavier than a completely dry hull. And removal of water that is being held somewhere in the hull in the foam is more or less impossible without rather drastic measures.
If there are openings in the gel coat layer of the hull that reveal underlying laminate layers, there might be some dampness in that area. But typically if the boat is left out of the water for a few months, some of that dampness will evaporate.
If there are damaged areas in the hull which are deep enough to expose the foam interior itself, and those areas are in sections that would normally be submerged when the boat was in the water, then more concern about moisture content is called for.
I would not obsess about the amount of hull weight due to retained water. All hulls have some weight due to water. As long as the boat floats at its intended waterline, you will be fine.
[Update: fixed error in weight of water by volume.]
https://continuouswave.com/whaler/reference/13/
Weighing the boat to one-tenth of a pound is not particularly necessary. I am sure that the variation in production of the boat would easily exceed one-tenth of a pound among all production hulls.
A 1970 hull should be a hull without the bow line "smirk", and with a notched transom designed for a 15-inch-shaft-length engine. A hull like that would weight somewhere around 250 to 275-lbs.
Water weights about [8.34 -lbs] per gallon, so if your hull had two gallons of absorbed water, it will only be 17-lbs heavier than a completely dry hull. And removal of water that is being held somewhere in the hull in the foam is more or less impossible without rather drastic measures.
If there are openings in the gel coat layer of the hull that reveal underlying laminate layers, there might be some dampness in that area. But typically if the boat is left out of the water for a few months, some of that dampness will evaporate.
If there are damaged areas in the hull which are deep enough to expose the foam interior itself, and those areas are in sections that would normally be submerged when the boat was in the water, then more concern about moisture content is called for.
I would not obsess about the amount of hull weight due to retained water. All hulls have some weight due to water. As long as the boat floats at its intended waterline, you will be fine.
[Update: fixed error in weight of water by volume.]
Re: Hull Weight of 1970 SPORT 13
Yes--posting too early today before coffee was ready and thinking about gasoline density, not water. Thanks for the gentle correction.
Re: Hull Weight of 1970 SPORT 13
I know my 13-foot hull has gained some weight over the years, but [the added weight] actually makes [the hull] feel more stable at speed. When [the hull] was new and dry, [the engine was a] an Evinrude 50-HP, and [the boat] was scary fast.
Re: Hull Weight of 1970 SPORT 13
As the weight of a hull increases while the propulsion power remains the same, the maximum hull speed will decrease. Perhaps your perception that adding weight increase the stability of the hull was a result of the boat speed decreasing.
If adding weight to a hull incurred no penalty and inherently increased stability, then all boats would be built as heavily as possible and still be able to float. That is clearly not a the case.
If adding weight to a hull incurred no penalty and inherently increased stability, then all boats would be built as heavily as possible and still be able to float. That is clearly not a the case.