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Old 08-11-2012, 02:17 AM   #1
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Boat hoist scale accuracy

How accurate have you found boat hoist scales to be?

We recently had a deal to buy a small 23' full displacement pocket cruiser fall apart because the scales read double what everybody, including the current owner, expected it to be. That put serious doubt into whether the trailer was up to the task, and extra serious questions as to what could cause such drastic weight gain.

The current owner had an old yachting magazine which contained an article about the boat that said it should have weighed 4,000 pounds, but the hoist scales showed almost 4,000 pounds per strap.

There wasn't too much extra "stuff" aboard when it was hoisted from its old trailer, the water tank was almost empty, as were the fuel tanks.

We contacted the surveyor again, and he said that hoist scales give ballpark figures because they don't read a vessels weight, but show an estimate based on the hydraulic pressure needed to lift it. He also said, "I imagine there may be some concrete in the inaccessible bilge area beneath the permanently screwed down sole..."

I can see the boat weighing quite a bit more than what the manufacturer claimed, especially if ballast was added at a later date to dampen roll...but twice as much?!!?

I'm going to call the owner tomorrow and see if he can take it to a truck weigh scale. If I remember correctly, he'll have to weigh the truck with the boat and trailer attached (to account for the weight on the hitch), weigh the boat and trailer while still attached to the truck, then subtract the truck and trailer to find the true weight of the boat.

Lots of navel gazing over this because we would need to have a new trailer built to drive it 1,000 miles from Vancouver to northern BC, and borrow a more powerful truck to tow with.

Advice / past experiences / wisdom?

Murray
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Old 08-11-2012, 06:05 AM   #2
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They are never use for weighing a sail boat to create a rating.

Not enough accuracy.
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Old 08-11-2012, 09:38 AM   #3
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Hey Murray, Was it a "Travel-lift" they were using? What boat yard was it in? I know when we put the "Salty Bear" up this spring the yard we used said she was 60% heavier than her paperwork read. However we did have 70% fuel on board and 50% water. I still can't see her weighing that much more.

Good luck, hope you get it straightened out.

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Old 08-11-2012, 10:46 AM   #4
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Thanks FF & Hello Kevin,

Yes, it was a "travel-lift" type hoist at the Reed Point Marina in Port Moody, BC.

You'd think they would have wee bit more accurate scales on those things...a person wants to know if their trailer and/or tires will survive 1,000 miles of Vancouver freeway repaving, interior plateau frost heaves, and Skeena River highway contortions!

(Saw one boat trailer that lost a tire on the Skeena section, on a corner, squeezed up against the cliff, with *just* enough room between the boat and the concrete barricade for transport trucks to squeeze by. Grim)

Murray
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Old 08-12-2012, 01:04 AM   #5
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If the trailer is designed for a 4000 pound boat and you put an 8000 pound boat on it, I think you'd flatten the springs. At any rate you should be able to see that something is wrong.

I had a small boat weighed a couple of years ago. I had an accurate trailer weight from the manufacturer. I drove the trailer onto the scale, unhitched from the truck, drove the truck off the scale and got an accurate weight.
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Old 08-12-2012, 06:18 AM   #6
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Simply go to a big truck stop , and have the unit weighed.

CAT brand scales guarentee their accuracy , and the cost is about $6.00.

Drive in ,stop the car with the trailer wheels alone on a square , and the tow vehicle on a different square, push the button , and talk to the speaker , like in a drive in food place.

Then go in and pay , and receive tour weight ticket.

Fast & cheap.
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Old 08-12-2012, 07:22 AM   #7
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My previous boat was listed bt the manudacturer at 4300 lb. Two years later when I weighed it, the actual weight was 6,000 lb.

Deducting fuel, water, and stuff I added, the actual weight was still more than 1,000 lb more than what the manufacturer had advertised.

My point is, the difference could be in the scale, the supposed actual weight, or both. If the boat has a trailer, tow them both to a public scale and weigh them. Then deduct the weight of the trailer to determine the actual boat weight.
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Old 08-12-2012, 08:16 AM   #8
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Travel-Lift scales are notoriously inaccurate and are biased towards reading high, as a safety precaution. Use the truck weighbridges
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Old 08-12-2012, 12:46 PM   #9
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Water absorption in hull core materials and flotation foam will cause a boats weight to increase a lot.
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Old 08-12-2012, 02:05 PM   #10
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"Water absorption in hull core materials and flotation foam will cause a boats weight to increase a lot."

Not really , Flotation foam is indeed crap not really designed to do more than float a flooded vessel for a while , till the rescue.

It should never be in water till its required.

Foam or other "structure" used as a core material may or may not absorb water.

The better foams like AIREX can be submerged with no loss almost forever.

Cheaper foams , who knows? And the seller sure wont tell.

Some foam plugs like inside a Boston Whaler will eventually absorb water when the hull or deck is breached.

Price Built Boats cheaper than a BW may gain hundreds of pounds

Balsa and Chinese composite can indeed be water logged , or simply dissolve .

Anyone want a 500lb 8 ft dink? Visit my place in FL for a free one , with papers.
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Old 08-12-2012, 11:46 PM   #11
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Will have the Coot hoisted soon for bottom treatment. Because of You, I'll have to ask what their scale reads (assuming they have one) and compare it to the builder's figures.

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