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Whameller
05-15-2012, 03:48 PM
I'm working with an architect friend to design a new workshop; it will be used for building boats up to 20' or so after I retire from the military in a couple of years time. Given my advancing years, I want to be able to build in the ability to use lifting tackle to assist with hull turnover, etc.

My question is - what is a good maximum weight estimate for a completed (but not fitted out) hull ?

Acknowledged that this is one of those 'How long is a piece of string ?' questions but if, for example, one specified the hull of a 19' gaff cutter rigged cruising boat - what would be an estimated weight for the hull if built:
- in traditional clinker
- in strip planking, epoxy sheathed
- cold moulded
- clinker ply/epoxy ?
Given some idea of this weight, we can specify the cross beams which will take the lifting tackle.

Many thanks in advance for any suggestions.

Nick

Mrleft8
05-15-2012, 04:18 PM
Figure on lifting your pick up truck with a chain hoist. At some point you're going to want to do that anyway if you can, so......
And you can get really fun lifty stuff from Northerntool.com
Stuff like wheelie things that you can dangle a hoist from, that run on the flange of an I-beam overhead......

Whameller
05-15-2012, 04:52 PM
Figure on lifting your pick up truck with a chain hoist. At some point you're going to want to do that anyway if you can, so......
.
Being a Brit, I have a Land Rover 110, not a pickup - but I do know that I'm going to have to lift the V8 out of it for a rebuild (its nearly 30 years old) sooner or later .... So about 1 1/2 tons then ?

Wayne Jeffers
05-15-2012, 05:01 PM
In the US, a pickup truck is more like 2 1/2 tons. IMO, this would be overkill.

A 20' hull, less interior fittings and ballast, should be no more than 1/2 ton. Turnover is likely to be more a rolling over, rather than lifting and flipping in mid-air, so weight lifted will be less.

I scattered 1/2-inch (~12mm) eye screws around the ceiling of my shop as points for tackle to assist with rollover.

Wayne

Duncan Gibbs
05-15-2012, 05:11 PM
http://pic80.picturetrail.com/VOL1913/10058894/24049698/401510547.jpg

Just under 1.7 metric tonnes of Dragon suspended from two 2x6" hardwood (Eucalyptus) beams via four chain and blocks.

Posts are two 2x4" bolted together at 600mm centres with a lap left up top for the beam and pre-bolted to take the braces.

Didn't even groan under the weight! :)

michaeljoseph
05-15-2012, 05:39 PM
Hi Nick, Mike from New England. I was going to start the same thread.I am a retired carpenter and am going to build a 20 x 12 workshop for restoring and building boats. My question was going to be should there be something I need to take in consideration as far as designing a workshop for boats. As far as lifting and flipping a boat I have thought of that. Two collar ties ( beams griders whatever) 4x8 or 4x10 should be fine. You are lifting from 4 points so the total weight will be divided by 4. Make sure you post down below them. Architects overbuilt everything. I have worked on houses here in new england from the 1700's and if you built a house the same way today the building inspecter would laugh at you and a architect would be sued; but these houses are still standing! Please post and let me know of any details I can use in my workshop. Cheers Mike..

TerryLL
05-15-2012, 06:44 PM
My last 20' boat weighed 2000 pounds. My current 20-footer will top out at about 350 pounds. But in my dream shop I'd have a 5-ton fully motorized bridge crane with at least 20' of ground clearance.

Whameller
05-16-2012, 03:45 AM
Many thanks for all the replies.I reckon that if we go for a planned weight of 1 1/2 (metric) tons distributed between 2 beams, that should do. The beams have a structural function, in any case, dealing with wind loadings on the walls in order to satisfy building regs.I'll report back on the design in due course; the build won't happen until either late this year or early next.Nick

Ron Williamson
05-16-2012, 05:05 AM
You also need a safety factor.
Breaking Strength versus Working Load Limit is 3 to 1,IIRC.

R

Mrleft8
05-16-2012, 06:36 AM
No sense in under-building it.... If you build it oversized (volume) you will simply fill it with more stuff. If you over-build it (strength) you will find something heavy to lift. It's just one of those unwritten rules of nature....

Wayne Jeffers
05-16-2012, 09:55 AM
. . . My question is - what is a good maximum weight estimate for a completed (but not fitted out) hull ? . . . if, for example, one specified the hull of a 19' gaff cutter rigged cruising boat - what would be an estimated weight for the hull if built:
- in traditional clinker
- in strip planking, epoxy sheathed
- cold moulded
- clinker ply/epoxy ?
. . .

It will be well enough if he could lift HMS Titanic, but he is asking the maximum weight of a 19' wooden sailboat hull at rollover.

Can anyone show me a 19' wooden sailboat with a bare hull weighing more than 1000 pounds?

Wayne

Tom Robb
05-16-2012, 03:43 PM
You could look at various wished-for plans and guestimated weights and build for that plus the usual engineering safety factor.
No matter how strong the crane or how large the shop, you'll probably end upwishing you'd planned for more.
At any rate, we'll all be jealous when it's done.

Reynard38
05-16-2012, 06:20 PM
Do your back a favor and use a wooden floor.

PeterSibley
05-16-2012, 07:36 PM
I am going to add an I beam along the center of my shed soon, the structure will hold it and the maximum envisaged loads would be around 500 kg / 1100 lb. It will have a traveller and chainblock running on it.

It's main function will be effortlessly moving machines and small boats around.

J.Madison
05-16-2012, 08:20 PM
My 20' gaff rigged cutter will weigh in at 5000 lbs when completed. That is a lot more than the other numbers being put in here. But don't just think about rollover of a bare hull- it would be mighty nice to be able to lift a boat off its trailer for painting and other maintenance, not to mention trailer maintenance. I'd say 5000 lbs is the max for a 20' boat, but there are certainly some out there that weigh more. And there are also some that weigh 300 lbs. There is your range.

Pete E
05-16-2012, 10:43 PM
I have a 42x60 pole building with 11foot celling The tresses for the roof are 2"x 12" for the bottom of the tress. I could safely lift 300 t0 500 lb. off the bottom of the tress. I wanted to be able to lift more so after talking to a carpenter I followed his suggestion. I screwed and glued 1/4" plywood too the side of the tress, from ceiling to the top of the tress. It took about six sheets of ply to cover the whole tress. At one point I put a lifting eye which was apiece of flat bar 4" wide 1/4" thick that went from the top of the tress to extending 4" below the tress. This should be able to lift 4000 lb. safely. I have marked on the lifting eye 2000 max lift.

Eventually in another part of the shop I will put in 4 lifting eyes. Two on a tress and mark them at 1000 lb. each. The tresses are about eight foot apart.

Incorporate your lifting right into the building right from the start. Unless you are going to be lifting all the time a crane is a waste or a steel I beam. Plywood on edge pound for pound is much stronger and a lot cheaper. Their are lots of examples of boats being rolled over with out being lifted, that seems to be a better way and I am some one who has lifted and move a lot of different things with cranes , chain falls and come a longs.

Whameller
05-17-2012, 03:56 AM
There's some really good points coming out here - many thanks to all. The walls of this workshop will by breeze block (US = cinder block ?), with piers to support the wooden roof beams - all resting on a reinforced concrete raft (raft required because of the nature of the subsoil). Some of the cross beams also have to serve as a tie-ins against wind loading on the walls. The site is in West Pembrokeshire (SW Wales) sticking out into the Atlantic, so wind is a significant issue in building around here. It is these beams that we have our eye on to support the lifting loads; we are now thinking of running another beam centrally down the workshop between the cross beams to allow lifting points to be adjusted as required along it - running the load calculations to see what the cost/benefit payoff of this might be. Nick

PeterSibley
05-17-2012, 04:16 AM
There's some really good points coming out here - many thanks to all. The walls of this workshop will by breeze block (US = cinder block ?), with piers to support the wooden roof beams - all resting on a reinforced concrete raft (raft required because of the nature of the subsoil). Some of the cross beams also have to serve as a tie-ins against wind loading on the walls. The site is in West Pembrokeshire (SW Wales) sticking out into the Atlantic, so wind is a significant issue in building around here. It is these beams that we have our eye on to support the lifting loads; we are now thinking of running another beam centrally down the workshop between the cross beams to allow lifting points to be adjusted as required along it - running the load calculations to see what the cost/benefit payoff of this might be. Nick

If you run a beam down the center I heartily recommend a traveller on that beam ,it gives complete flexibility but also allows you to move equipment and boats effortlessly.

skuthorp
05-17-2012, 05:34 AM
I have a 20 ton I beam fitted in the roof of a steel framed agricultural shed with a 2 ton chain hoist as this is as much as i'll ever need. The beam was second hand and was the right length, the rating was incidental. It is a very handy piece of kit.

Bob Cleek
05-17-2012, 01:13 PM
Having a traveling hoist on a beam is a wonderful convenience, when you need it, but ask yourself, "How many 20 foot boats am I really going to have to roll?" Let's face it, probably not many. Considering the engineering costs and all, you may find it a lot more economical and efficient to simply roll the boat out of the shed and flip her with a rented crane, or, depending on the weight, just get a bunch of friends and a few cases of beer and roll her over onto a bunch of old tires for cushioning. If she is so heavy that she can't be rolled by the local rugby team, you're probably better off building it right side up in the first place.

SamSam
05-17-2012, 02:41 PM
You might also be able to temporarily brace any beams if the lift is too heavy.

PeterSibley
05-17-2012, 04:55 PM
Having a traveling hoist on a beam is a wonderful convenience, when you need it, but ask yourself, "How many 20 foot boats am I really going to have to roll?" Let's face it, probably not many. Considering the engineering costs and all, you may find it a lot more economical and efficient to simply roll the boat out of the shed and flip her with a rented crane, or, depending on the weight, just get a bunch of friends and a few cases of beer and roll her over onto a bunch of old tires for cushioning. If she is so heavy that she can't be rolled by the local rugby team, you're probably better off building it right side up in the first place.


A beam traveller costs about $200 for the best manually operated one Bob, $100 for a cheap one. Good for boats but the main use is shifting equipment around in a (sometimes) crowded workshop, over other gear, stacks of timber and such.

Wayne Jeffers
05-17-2012, 05:40 PM
. . .

Can anyone show me a 19' wooden sailboat with a bare hull weighing more than 1000 pounds?

Nick,

Consider carefully that no one has taken up my challenge to name a 19' wooden sailboat bare hull weighing more than 1000 pounds. (Most bare hulls will be lighter.)

Consider too the snow load your roof will be engineered to support. One thousand pounds of bare hull spread over 2 or more points will be well within the weight-bearing range of your roof trusses. Ask your architect!

If you want to hoist heavy boats, that's something else entirely. But if you want to turn a few small sailboat hulls, there's no need to go to great trouble and expense.

Wayne

Duncan Gibbs
05-17-2012, 05:56 PM
Consider carefully that no one has taken up my challenge to name a 19' wooden sailboat bare hull weighing more than 1000 pounds. (Most bare hulls will be lighter.)

Ahem...


My 20' gaff rigged cutter will weigh in at 5000 lbs when completed.

Even without 1,500 lbs of ballast, 300-400 lbs of rig, 200-300 lbs of engine and 1000 lbs of deck, coach roof and fit-out it's still above 1000 lbs of hull. Why build under capacity when it's just as easy to build up to capacity. I didn't know I'd be lifting a Dragon off a trailer...

the_gr8t_waldo
05-17-2012, 06:30 PM
if you have the "where with all" mount the chain fall on a traveling bridge. this will allow unlimited places to lift from, and the ease of moving loads to any location in the covered area. if all you want to do is lift a hull , make a gallows type frame to take the load, and when completed it could be broken down and stored.

Wayne Jeffers
05-17-2012, 08:53 PM
Even without 1,500 lbs of ballast, 300-400 lbs of rig, 200-300 lbs of engine and 1000 lbs of deck, coach roof and fit-out it's still above 1000 lbs of hull. Why build under capacity when it's just as easy to build up to capacity. I didn't know I'd be lifting a Dragon off a trailer...

Are you familiar with this 20' boat? Does that 5000 pounds also include crew and cruising stores, i.e., is it the rated displacement, rather than the weight of the boat?

The OP's original question was the weight of a 19' bare wooden hull. There may be the exceptional 19' bare hull that weighs more than 1000 pounds, but I have yet to see satisfactory evidence of one. (And, please, don't anyone point to the weight of boats longer than 19', as we all know weights increase exponentially with length.)

He asked specifically about a 19' gaff cutter. As an example of that type, the displacement of a Cape Cutter 19 to DWL is 2425 lbs., weight of the finished boat (no crew or stores) is stated at 1918 pounds, including 838 pounds of ballast. Of the 1080 pounds w/o ballast, I feel confident that the bare hull will be well under 700 pounds, without rig or interior fittings.

In any event, life is full of choices. If he chooses to construct a system to lift and move 5000 pounds (or more,) I certainly have no quarrel with that. But I don't think telling him he needs that is responsive to his question.

Perhaps if he cited some examples of the designs he has in mine, some of us could give him more concrete weights.

Wayne

Duncan Gibbs
05-17-2012, 10:29 PM
Wayne, I see the value of what you're saying but the detail and numbers are at variance to the gist of your argument.

I've been through some pretty detailed studies of weights in Atkins' boats including MOE, Eric Jr and my own variation and enlargement of Eric Jr, Erica. I can say with a fair degree of certainty that the bare hull weight of MOE is about the 1500 - 1700 lbs mark depending on the SG/Cubic volume weight of the timber used, and that does not include the moulds, which would have to remain in place for any hull flipping to ensure the hull shape remained fair. I can think of a great many traditional British 18 to 22' gaff cutters that displace more than 3 tonnes, from which you can conclude the bare hull weight will be at least a sixth of the final displacement. There are at least a dozen Harrison Butler designs that fit the bill as well. CP Kundhardt's book Small Yachts is awash with like vessels.

Now to the building itself: You stated...


Consider too the snow load your roof will be engineered to support. One thousand pounds of bare hull spread over 2 or more points will be well within the weight-bearing range of your roof trusses. Ask your architect!

If you want to hoist heavy boats, that's something else entirely. But if you want to turn a few small sailboat hulls, there's no need to go to great trouble and expense.


The bit in bold is entirely correct and I point to my own exercise pictured above in my first post to this thread.

The second statement makes no sense in relation to the section in bold and the point about snow loading. Trusses or beams need to span space and support the roofing structure; purlins, battens, iron/tiles/shingles, and snow loads. These bearing structures are required to support their own weight, the roof and the the 'moment' of the material being used. In all the structures I've designed I've found that there's not a great deal of difference in cost or effort by adding to the structural ability of a roof.

As well there are all the other reasons for doing so in a workshop environment so that things can be lifted up off trailers and put down and moved around by using to trusses and beams of the roof with blocks and chains and the like.

Not to build such capacity into a purpose built workshop would be, IMHO, really quite remiss.

Whameller
05-18-2012, 05:30 AM
Again, many thanks for all the points coming out here. To answer some of the questions that have come up WRT my OP ..... (1) Hard to be exact about what boats will be involved but my first post-retirement project will be building either a Welsford 'Pilgrim' (stretched by 10% to 5.5m) or a Vivier Ebihen 18. I will be retraining (beyond my current amateur level of skill) as a wooden boatbuilder over a 2 year period post retirement, during which I will be doing this first build. I then hope to find sufficient work either in repair or new commisions of small woooden boats top top up my Army pension and keep me active. A 19-20' (of whatever conformation or rig) represents the largest project that I see myself undertaking working alone - hence taking it as the greatest load likely to be required to be lifted from 2 points; an inboard engine for such a craft would be the largest load from a single point. (2) I'm not sure that we take snow load on the roof as a major design factor in West Wales - the Eastern Atlantic climate gives us (except in truly rare winters) more challenges with wind and rain. The roof material is corrugated metal on wooden trusses. In any case, surely that is a compression load on the roof & wall structure and the lifting loads work in another vector altogether ? Overall, I want to be able to design in from the start the flexible ability to lift 'things' in general that Duncan describes above. Thanks again. Nick

Tom Robb
05-18-2012, 05:05 PM
Pete E, post #16
Please, before you hang any significant load on the bottom cord of a truss, consult the manufacturer of the truss.
They aren't engineered for that sort of load, IIRC.
Tom