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Author Topic:   Water in my hull?

smgrogue posted 10-05-2002 02:03 AM ET (US)
This is one of those "what should my boat weigh" questions. Due to the possibility that I may have water in my hull as a result of gel damage left unrepaired by previous owner, I decided to weigh my 1981 Striper 15. I removed fuel tank, batteries, cooler seat--everything that wasn't connected to the boat. Remaining items left attached to boat were as follows:
1) motor (35 evinrude 2s--dealer says weighs 120lbs...dont know if that includes prop);
2) Evinrude "Scout" 12/24 volt trolling motor w/cable foot control, plus a couple of empty battery boxes screwed to deck;
3) Console & rigging (steering cable, fuel & elec lines, etc)
4) Stainless steel side rails plus separate "montauk style" bow rail;
5) Factory rear and front (Pick Industries) swivel seats; and a couple of slighty soggy life jackets if foregot to take out of bow hatch.
The above weighed 840 lbs according to a certified truck scale (...weighed boat on/off trailer). In view of all this, does anyone care to speculate on whether I may have some water in my hull...or more to the point, enough water to worry about.
This winter I will be addressing the aforementioned hull damage, and I want to know if I need to go hunting for water pockets. I really have not found any suspicious spots using the tapping method, buy maybe I'm not doing it right. As always, thanks in advance for the help. Stephen

jimh posted 10-05-2002 09:00 AM ET (US)
As the FAQ describes and your question affirms, assessing the water content of a hull by weighing it is a difficult proposition.
Having weighed your hull at present, you might be able to use this information in the future to make comparisons, but it is impossible to know the precise weight of your hull when new and dry.
How interesting if Whaler had recorded the hull weight at the factory!
Since water weights less than 7-lbs. per gallon, one could have as much as ten gallons of water in the hull and still see less than 70-lbs. variation from the stock weight.
Generally, weighing the hull will only reveal gross overweight conditions caused by water ingress.
Tom W Clark posted 10-05-2002 10:39 AM ET (US)
Stephen,
As jimh points out, it is very difficult to determine if there is a small amount of water in the hull. Lets review the information you have provided:
1981 Striper - 550 lbs (if memory serves me correctly)
c. 1981 Evinrude 35 long shaft - 120 lbs
Evinrude Scout electric trolling motor - ?
optional bow rail - 15 lbs
soggy life jackets - 5 lbs
The catalog listed hull weigh of a given model includes the weight of the console, seats and standard rigging like steering cable but not the outboard controls.
So based on the information provided I would speculate that your boat should have weighed 740 lbs, but what if the boat actually left the factory weighing 600 lbs? What if the outboard and its controls actually weigh 150 lbs?
The only thing we can really tell is that the hull is not totally soggy. It could be that are a few (or 15 or more) gallons of water in there or not.
As far a tapping of the hull goes, that will only reveal a hollow area in the foam right next to the fiberglass skin. This is how the technique is used at the factory for new hulls. For used hulls it may reveal delamination of the fiberglass skin from the foam.
This has little or nothing to do with the problem of soggy foam. Saturated foam is still quite firm and remains perfected adhered to the fiberglass skins. It does not turn mushy or breakdown as the result of water absorption.
Even if your hull has a hundred pounds of water in the foam I would guess it is still as sound a hull as when new but with the reduced weight capacity and accompanying performance loss of that extra weight.
David Jenkins posted 10-05-2002 01:29 PM ET (US)
Maybe the biggest danger to having some water in the hull is that it could cause damage to the fiberglass when it freezes?
smgrogue posted 10-05-2002 08:11 PM ET (US)
Thanks to all for your replies. After further research and measurement I now have the boat down to about 30 lbs that I cannot account for. From all your comments I am comfortable that this is well within the margin of errror. Or as Tom pointed out, even if there's 30 lbs of water in there its not enough to make a performance difference. I'd be interested in knowing whether anyone thinks there is any merit to the freezing issue that David raised.
By the way David, do you have any reports for us yet on the performance of that DF70 on your 15?
lilgypsy2000 posted 10-05-2002 11:35 PM ET (US)
Ummm just a minor correction as to the weight of water. It weighs 8.33 lbs. per gallon. Just my $.02 worth.
David Jenkins posted 10-05-2002 11:43 PM ET (US)
I have not repowered but intend to do so this fall. I bought the boat this summer and want to take care of some crazing in the gelcoat and put some varnish on the mahogany, then put on the jackplate and new engine. I just bought new rails for it and a 9' Squall for the kids, and I am repainting our house, adding hardwood floors, and selling real estate. There are not enough hours in the day. Thanks for your interest--I'll let you know how it turns out.
jimh posted 10-06-2002 04:59 PM ET (US)
Thanks for the correction of the weight of one gallon of water. (See http://mathforum.org/library/drmath/view/56355.html )
This works out to about 62-lbs./cubic-foot.

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Author	Topic: Water in my hull?
smgrogue	posted 10-05-2002 02:03 AM ET (US) This is one of those "what should my boat weigh" questions. Due to the possibility that I may have water in my hull as a result of gel damage left unrepaired by previous owner, I decided to weigh my 1981 Striper 15. I removed fuel tank, batteries, cooler seat--everything that wasn't connected to the boat. Remaining items left attached to boat were as follows: 1) motor (35 evinrude 2s--dealer says weighs 120lbs...dont know if that includes prop); 2) Evinrude "Scout" 12/24 volt trolling motor w/cable foot control, plus a couple of empty battery boxes screwed to deck; 3) Console & rigging (steering cable, fuel & elec lines, etc) 4) Stainless steel side rails plus separate "montauk style" bow rail; 5) Factory rear and front (Pick Industries) swivel seats; and a couple of slighty soggy life jackets if foregot to take out of bow hatch. The above weighed 840 lbs according to a certified truck scale (...weighed boat on/off trailer). In view of all this, does anyone care to speculate on whether I may have some water in my hull...or more to the point, enough water to worry about. This winter I will be addressing the aforementioned hull damage, and I want to know if I need to go hunting for water pockets. I really have not found any suspicious spots using the tapping method, buy maybe I'm not doing it right. As always, thanks in advance for the help. Stephen
jimh	posted 10-05-2002 09:00 AM ET (US) As the FAQ describes and your question affirms, assessing the water content of a hull by weighing it is a difficult proposition. Having weighed your hull at present, you might be able to use this information in the future to make comparisons, but it is impossible to know the precise weight of your hull when new and dry. How interesting if Whaler had recorded the hull weight at the factory! Since water weights less than 7-lbs. per gallon, one could have as much as ten gallons of water in the hull and still see less than 70-lbs. variation from the stock weight. Generally, weighing the hull will only reveal gross overweight conditions caused by water ingress.
Tom W Clark	posted 10-05-2002 10:39 AM ET (US) Stephen, As jimh points out, it is very difficult to determine if there is a small amount of water in the hull. Lets review the information you have provided: 1981 Striper - 550 lbs (if memory serves me correctly) c. 1981 Evinrude 35 long shaft - 120 lbs Evinrude Scout electric trolling motor - ? optional bow rail - 15 lbs soggy life jackets - 5 lbs The catalog listed hull weigh of a given model includes the weight of the console, seats and standard rigging like steering cable but not the outboard controls. So based on the information provided I would speculate that your boat should have weighed 740 lbs, but what if the boat actually left the factory weighing 600 lbs? What if the outboard and its controls actually weigh 150 lbs? The only thing we can really tell is that the hull is not totally soggy. It could be that are a few (or 15 or more) gallons of water in there or not. As far a tapping of the hull goes, that will only reveal a hollow area in the foam right next to the fiberglass skin. This is how the technique is used at the factory for new hulls. For used hulls it may reveal delamination of the fiberglass skin from the foam. This has little or nothing to do with the problem of soggy foam. Saturated foam is still quite firm and remains perfected adhered to the fiberglass skins. It does not turn mushy or breakdown as the result of water absorption. Even if your hull has a hundred pounds of water in the foam I would guess it is still as sound a hull as when new but with the reduced weight capacity and accompanying performance loss of that extra weight.
David Jenkins	posted 10-05-2002 01:29 PM ET (US) Maybe the biggest danger to having some water in the hull is that it could cause damage to the fiberglass when it freezes?
smgrogue	posted 10-05-2002 08:11 PM ET (US) Thanks to all for your replies. After further research and measurement I now have the boat down to about 30 lbs that I cannot account for. From all your comments I am comfortable that this is well within the margin of errror. Or as Tom pointed out, even if there's 30 lbs of water in there its not enough to make a performance difference. I'd be interested in knowing whether anyone thinks there is any merit to the freezing issue that David raised. By the way David, do you have any reports for us yet on the performance of that DF70 on your 15?
lilgypsy2000	posted 10-05-2002 11:35 PM ET (US) Ummm just a minor correction as to the weight of water. It weighs 8.33 lbs. per gallon. Just my $.02 worth.
David Jenkins	posted 10-05-2002 11:43 PM ET (US) I have not repowered but intend to do so this fall. I bought the boat this summer and want to take care of some crazing in the gelcoat and put some varnish on the mahogany, then put on the jackplate and new engine. I just bought new rails for it and a 9' Squall for the kids, and I am repainting our house, adding hardwood floors, and selling real estate. There are not enough hours in the day. Thanks for your interest--I'll let you know how it turns out.
jimh	posted 10-06-2002 04:59 PM ET (US) Thanks for the correction of the weight of one gallon of water. (See http://mathforum.org/library/drmath/view/56355.html ) This works out to about 62-lbs./cubic-foot.