Thoughts on weighing boats and waterline placement

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Author Topic:   Thoughts on weighing boats and waterline placement

jameso posted 02-20-2003 03:03 PM ET (US)
We, the members of this forum, spend a lot of time discussing weights of boats and how the weight affects the performance. We also wonder if we are buying a waterlogged hull or if we have some water intrusion. We weigh and pray and still often wonder.
Why not use the vast knowledge of this forum to develop a weight/waterline table? Here is what I propose; For each individual boat we use 4 reference points, two of these points would be on each side of the transom. The other two could be a given distance aft of the bow, or on a given model a certain feature. In other words my 15’s would be referenced at the transom and say the aft side of the anchor locker bulkhead. By measuring from the top of the gunnels to the waterline a reference could be established. Of course each model and how it is rigged would be different but a good standard could be established.
OK here is what members could do, Nick could measure this Newport with the 88 OMC list loads as to batteries, fuel ect. Clark could do the same with several of his fleet and of course the 13’s and the 15’s would be well represented. A few minutes at the launch ramp or a beach would be all it would take, get out of the boat and do a walk around with the tape and maybe a china marker.
Using this data, if you were in the market for a boat you would take the measurement of it and compare it to the chart, also when performance tweaking you could use the other members data to compare your craft.
This is the way weights of larger ocean going vessels are determined. Maybe not rocket science, maybe not of value. Just thinking.
Jim Armstrong

Bigshot posted 02-20-2003 03:25 PM ET (US)
Great idea but.....many of us are in salt water and many in fresh. Water temp and salinity make a big difference in static trim as well as speed. I persoanlly look at where the engine sits and where any bottom paint lines have been 'increased" do to squating further down into the abyss. This newport sits higher than my montauk but 2 things are considered, the engine and sans jackplate are lighter and the "cap" adds weight to the bow. Believe it or not a heavy anchor with chain will change static trim very much. If I add 20lbs to my anchor locker, the drain ports in the motor well will lift almost an inch.
elaelap posted 02-21-2003 08:47 PM ET (US)
Jim--And some of us might just not want to know.
Unlike you, I'm no rocket scientist; when it comes to boats I live part of my life in a land of intuition and make-believe. I've only had my 32-yr-old Katama out five times since I bought her last October, and those times with a now-replaced ancient 50 hp motor and dinged-up prop. Each time she lumbered up onto plane in 6-8 seconds, and topped out at about 30 mph...fast enough to have my rowdy 16-yr-old son telling me to slow down, for the first time in his miserable, raucous teenage life.
I've read with fascination and dismay about wet hulls and open versus closed cell foam in the older Whalers, and frankly don't want to know whether my tightly corseted old lady is fifty or a hundred pounds overweight...it just doesn't seem polite to her to probe too deeply, literally and figuratively. My boat's got a great hull, no holes, dry as toast to my loving eyes, and if a little ocean has made its way inside in three decades, I just don't want to know. As an aerospace guy, you care a lot about such matters, and that's great, you better; but as a mere mortal, I beg you --please don't make me lie awake at night worrying about my gal's possible weight problems; I'd much rather worry about my own flabby bod.
Tony
JoeH posted 02-22-2003 10:43 PM ET (US)
I weighed my Outrage at a local gravel pit for $5. So now I have a number but how was it done at the factory? Just a hull, with or without console, seats, fittings/rails, hatches, etc.? Joe
Tom W Clark posted 02-23-2003 10:38 AM ET (US)
JoeH,
The specified weight of a given Whaler was for that particular model.
In the case of, oh let's say a 1992 Outrage 19, the weight is listed as 1900 pounds. That would include the console, seats, rails, cleats, steering cable and wheel and any and all accessories that came standard on that model.
The weight would NOT include the trailer, motor, battery, or fuel in the tank.
JoeH posted 02-24-2003 06:58 PM ET (US)
Tom, Thank you. Now I just need to double check the trailer without the boat this summer against the registration for my total. Joe
Jerry Townsend posted 02-25-2003 12:46 AM ET (US)
The biggest problem with using the draft to determine the weight is - the sensitivity and accuracy would be totally unacceptable. That is, one would be hard pressed to be able to read the draft to within +/- 1/2 inch because of the surface motion of the water and the motion of the boat. Then for example, with a hull that is 7 feet wide and say an equivalent rectangular length of 12 feet, that +/- 1/2 inch translates to +/- 218 pounds - which, in my mind is not close enough for any real purpuse. ---- Jerry/Idaho

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Author	Topic: Thoughts on weighing boats and waterline placement
jameso	posted 02-20-2003 03:03 PM ET (US) We, the members of this forum, spend a lot of time discussing weights of boats and how the weight affects the performance. We also wonder if we are buying a waterlogged hull or if we have some water intrusion. We weigh and pray and still often wonder. Why not use the vast knowledge of this forum to develop a weight/waterline table? Here is what I propose; For each individual boat we use 4 reference points, two of these points would be on each side of the transom. The other two could be a given distance aft of the bow, or on a given model a certain feature. In other words my 15’s would be referenced at the transom and say the aft side of the anchor locker bulkhead. By measuring from the top of the gunnels to the waterline a reference could be established. Of course each model and how it is rigged would be different but a good standard could be established. OK here is what members could do, Nick could measure this Newport with the 88 OMC list loads as to batteries, fuel ect. Clark could do the same with several of his fleet and of course the 13’s and the 15’s would be well represented. A few minutes at the launch ramp or a beach would be all it would take, get out of the boat and do a walk around with the tape and maybe a china marker. Using this data, if you were in the market for a boat you would take the measurement of it and compare it to the chart, also when performance tweaking you could use the other members data to compare your craft. This is the way weights of larger ocean going vessels are determined. Maybe not rocket science, maybe not of value. Just thinking. Jim Armstrong
Bigshot	posted 02-20-2003 03:25 PM ET (US) Great idea but.....many of us are in salt water and many in fresh. Water temp and salinity make a big difference in static trim as well as speed. I persoanlly look at where the engine sits and where any bottom paint lines have been 'increased" do to squating further down into the abyss. This newport sits higher than my montauk but 2 things are considered, the engine and sans jackplate are lighter and the "cap" adds weight to the bow. Believe it or not a heavy anchor with chain will change static trim very much. If I add 20lbs to my anchor locker, the drain ports in the motor well will lift almost an inch.
elaelap	posted 02-21-2003 08:47 PM ET (US) Jim--And some of us might just not want to know. Unlike you, I'm no rocket scientist; when it comes to boats I live part of my life in a land of intuition and make-believe. I've only had my 32-yr-old Katama out five times since I bought her last October, and those times with a now-replaced ancient 50 hp motor and dinged-up prop. Each time she lumbered up onto plane in 6-8 seconds, and topped out at about 30 mph...fast enough to have my rowdy 16-yr-old son telling me to slow down, for the first time in his miserable, raucous teenage life. I've read with fascination and dismay about wet hulls and open versus closed cell foam in the older Whalers, and frankly don't want to know whether my tightly corseted old lady is fifty or a hundred pounds overweight...it just doesn't seem polite to her to probe too deeply, literally and figuratively. My boat's got a great hull, no holes, dry as toast to my loving eyes, and if a little ocean has made its way inside in three decades, I just don't want to know. As an aerospace guy, you care a lot about such matters, and that's great, you better; but as a mere mortal, I beg you --please don't make me lie awake at night worrying about my gal's possible weight problems; I'd much rather worry about my own flabby bod. Tony
JoeH	posted 02-22-2003 10:43 PM ET (US) I weighed my Outrage at a local gravel pit for $5. So now I have a number but how was it done at the factory? Just a hull, with or without console, seats, fittings/rails, hatches, etc.? Joe
Tom W Clark	posted 02-23-2003 10:38 AM ET (US) JoeH, The specified weight of a given Whaler was for that particular model. In the case of, oh let's say a 1992 Outrage 19, the weight is listed as 1900 pounds. That would include the console, seats, rails, cleats, steering cable and wheel and any and all accessories that came standard on that model. The weight would NOT include the trailer, motor, battery, or fuel in the tank.
JoeH	posted 02-24-2003 06:58 PM ET (US) Tom, Thank you. Now I just need to double check the trailer without the boat this summer against the registration for my total. Joe
Jerry Townsend	posted 02-25-2003 12:46 AM ET (US) The biggest problem with using the draft to determine the weight is - the sensitivity and accuracy would be totally unacceptable. That is, one would be hard pressed to be able to read the draft to within +/- 1/2 inch because of the surface motion of the water and the motion of the boat. Then for example, with a hull that is 7 feet wide and say an equivalent rectangular length of 12 feet, that +/- 1/2 inch translates to +/- 218 pounds - which, in my mind is not close enough for any real purpuse. ---- Jerry/Idaho