Author Topic: weighing a boat  (Read 70 times)

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Offline Owly055

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weighing a boat
« on: November 19, 2017, 08:20:32 PM »
     The trimarans I'm interested in are extremely weight sensitive and have a fairly small envelope between empty weight and loaded weight.   In one case it's only 1500 lbs, in the larger one it's 2500 lbs payload.   1500 pounds is not much considering two people and their personal gear will take up about 1/3 of that, not including food and water, fuel, spares, tools, etc.    I personally would consider it next to impossible to stay within those parameters on an ocean crossing with two people with a reasonable margin on food and water, and sufficient spares and safety gear, electronics, etc.    With a crew of two, it would realistically be limited to coastal hops, and quite likely running over loaded even then, but in coastal sailing, one can fly within a weather window and get away with it.

     The point here is how can a person weigh a boat?  If the water line is positioned correctly, you can see if it is riding above or below the water line, but that only tells you that there is room for weight to be added, not how much, unless the designer has a chart available.   Part of the purchase process / survey, needs to be weighing the boat.  How many boatyards have a crane with a load cell, or a travel lift with a load cell?   The only other way I can see to determine empty weight, assuming the water line is accurate is to start packing 50 pound bags of sand or whatever aboard.  A used boat is always going to have some payload aboard when one looks at it, and many of those items of payload will probably go with it... that complicates the picture, as those items would need to be estimated at least.

     Home builders virtually always over build, and those little bits here and there are going to add up to hundreds of pounds, even multiple layers of paint added atop each other add significant weight.  On a monohull it's not too much of an issue, on a multihull it can be a make or break factor.  An overweight pig is not of any value at all to me.  Loaded the performance is going to suffer, but worse by far is the fact that safety will also suffer, as will comfort.   I'll likely be forced into a larger boat than I really want anyway just to get an extra 1000 pounds of payload, some of which will likely be taken up by the boat being over built or things added on that add up in weight.   How much does that pretty hard dodger add to the weight, the refrigerator, and the extra batteries and solar panels and wind charger that it requires, the fancy marine head and holding tank, the pump and plumbing for fresh water and salt water, the water heater, water maker, the fancy dual voltage wiring and breaker panel.  The larger boat is going to most likely have more amenities, but at least I could rip a lot of those out.  I really don't want or need plumbing and pumps, hot and cold running water..... or any running water a flush toilet, etc.   I don't need heavy fixtures, AC wiring, a TV / entertainment system, a microwave, food processor, or any of those things husbands install on boats to make their wives happy.   At least on the larger boat, there will likely be a lot of things I can remove!

                                                          H.W.

Offline CharlieJ

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Re: weighing a boat
« Reply #1 on: November 19, 2017, 11:27:15 PM »
I built a Cross 35 trimaran. At launch the crane operator told me 4500 pounds dry At cruising load, with three aboard full time, ALL our clothes (full time live-aboards), we figured we added another two tons. Anchors, etc probably another 2. So I figure we cruised at around 8500 to 9500 pounds. Not bad for a 35 foot trimaran. Secret is DON'T put all the poop aboard- and that's the boat that had a 3 burner kero stove, with oven.

And most if not all crane operators can tell within a few hundred pounds what they are lifting. On my tri we had to use a 50,000 pound travel lift, due to the boat beam- 20 feet.

On several occasions we saw 18-19 knots on a reach, This with two dinghies aboard. Came down the Chesapeake, running dead before hard winds, with main and jib, mizzen down, logging a steady 14 knots for over two hours in open bay (running for shelter before a HUGE front hit)

While it is true that multihulls need to be watched for over loading, it ain't that hard to NOT overload. By the way- three of us-me, wife and teenage boy, lived aboard full time for over three years. And cruised the east coast. In our last year aboard, the boat never touched a dock

I must admit I'm somewhat of a minimalist in on board gear though. No frig, no AC, none of my boats has ever had 115 volt wired aboard. Always just 12 volt, with either solar or a wind generator

I love multis, especially tris. But at my age I just do not want to maintain a multi with multi hulls- I've got all I want keeping 25 foot mono in top trim:)
Charlie J
Sailing on S/V Tehani
Meridian 25

On Matagorda Bay
On the Redneck Riviera

Offline Owly055

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Re: weighing a boat
« Reply #2 on: November 20, 2017, 09:44:38 AM »
     45 dry is impressive for a 35 foot tri.    Searunner and Cross are about the only tri's I consider suitable for my use.  I don't consider a mono acceptable as a live aboard voyager cruiser in this day and age.  Either as tri or a cat.  I want an unballasted boat that doesn't wear you out heeling for weeks at a time on passage or rocking crazily on a light wind downwind passage, or in an anchorage with a swell.  I don't have the energy to deal with living on my ear or  having to tie myself into my berth.
     If I had my "druthers" as we say here, I would probably go with a Bernd Kohler KD860 catamaran, but they simply are not available on the used market, and if they were they would not be within my price range.  I don't intend to burn up all my resources buying a boat, and then not have a cruising kitty.  I'm not interested in having to work to support a boat I can't really afford, though it's a boat I could build in a reasonable amount of time.   Here's a brief description.   28 feet long, 18' beam, open bows with netting as a cruising cat should be, high bridge deck clearance, but low profile....... bridge deck cabin is not standing headroom, but that's fine with me, the two companionways alleviate that considerably, and on the Searunners, two of the most used areas lack standing headroom, only the galley and the dressing room have standing room.    The hulls are flat bottom with no dagger boards, no keels, and no centerboards, and instead use anti vortex panels that are horizontal, and yet the boat is said to be able to sail closer to the wind than many monohulls, and not have a lot of side draft.  Standing headroom in both hulls, and lots of space.   Double berths forward of the saloon, roomy cockpit with standing visibility over top of the cabin, especially off to the sides, and best of all 2640 pounds of payload.   Two load bearing hulls out of two, instead of one out of three, makes sense to me.   Plywood epoxy construction just like a Searunner.   3960 lbs empty weight, 6600 lbs to waterline.   The 3960 empty weight against the 5500 on the searunner 31, and the 4500 on your cross brings some questions to mind.  It makes sense next to the cross, but not the Searunner, suggesting that the Searunner empty weight includes a lot more stuff in the empty weight.  It's difficult if not impossible to decipher what empty weight or dry weight means to different designers.    All in all I like the small size and abundant space on this boat.   2 28' hulls that are not interrupted by a center cockpit with a centerboard beneath it and the compartment forward of it, plus a bridge deck, adds up to a lot more internal space than a searunner hull.   Build cost would probably be higher, but not by much, though the weight suggests otherwise, but at 62, I don't want to take on a building project of that magnitude, nor am I laboring under the illusion that you can build for what you can buy used for...... There is a lot more than just hulls to finishing a boat.

    I'd hate to be in a boat at sea in the weather we're having here at the moment............ Gusty winds hitting 80+ mph.  Not uncommon here, but I still worry about my roof.

                                                                   H.W.

I built a Cross 35 trimaran. At launch the crane operator told me 4500 pounds dry At cruising load, with three aboard full time, ALL our clothes (full time live-aboards), we figured we added another two tons. Anchors, etc probably another 2. So I figure we cruised at around 8500 to 9500 pounds. Not bad for a 35 foot trimaran. Secret is DON'T put all the poop aboard- and that's the boat that had a 3 burner kero stove, with oven.

And most if not all crane operators can tell within a few hundred pounds what they are lifting. On my tri we had to use a 50,000 pound travel lift, due to the boat beam- 20 feet.

On several occasions we saw 18-19 knots on a reach, This with two dinghies aboard. Came down the Chesapeake, running dead before hard winds, with main and jib, mizzen down, logging a steady 14 knots for over two hours in open bay (running for shelter before a HUGE front hit)

While it is true that multihulls need to be watched for over loading, it ain't that hard to NOT overload. By the way- three of us-me, wife and teenage boy, lived aboard full time for over three years. And cruised the east coast. In our last year aboard, the boat never touched a dock

I must admit I'm somewhat of a minimalist in on board gear though. No frig, no AC, none of my boats has ever had 115 volt wired aboard. Always just 12 volt, with either solar or a wind generator

I love multis, especially tris. But at my age I just do not want to maintain a multi with multi hulls- I've got all I want keeping 25 foot mono in top trim:)