Lifting a boat

[akirk]

I recently acquired a 16' wooden launch ( Original thread showing photos ) and need to lift it off the trolley so that I can use the trolley for another boat.

Fortunately it is in a barn on a farm and the farmer is very happy to use a bit of machinery with prongs on the front to lift the boat.

I want to make something which we can use to lift her, and then keep in case we need to move her...

I was thinking of rope attached to a ring so that there are two rings for the two prongs on the machine, and from each ring we could run several loops of rope each adjustable in size to fit the hull as appropriate

I think that we need the ability to have loops which are fastened after going around the hull as the stern one will need to go through the space between hull and keel...

what have others done / bright ideas?

cheers

 

[ms1]

if lifting via a rope through a ring would this not exert quite a lot of pressure on the side of the boat - a crushing action. I woul imagine that it may be safer to use ropes/ straps etc which are held apart (above the boat) so as not to risk any crush damage

 

[sarabande]

If your friendly farmer (aren't they all ?!) is using a buck rake, I'd certainly use lifting straps rather than rope.

Given the shape of the hull , to prevent the sides being squeezed in the lifting process, make sure that the straps from the gunwhales upwards, are vertical (think of a "U" shape as the cross-section)

 

[Lakesailor]

The Steamboat museum is shortly going to lift many wooden boats from the water and everyone is eager to see what happens.
Even if you space the straps above deck level ther will be a crushing force on the turn of the bilges. In water the boat is gently held by water all the way along the hull. Two straps will apply forces in just two places.

Until you know how strong it is I would suggest lifting from below the keel, using a strong beam. You could roll it back off the trailer onto a beam

 

[cliffordpope]

True in theory. But surely in practice boats are capable of taking distinctly ungentle loadings, from bridging between short waves, direct wave impact, and when running aground and leaning on a single unfortunately-placed point of contact.
Unless the boat is an old wreck on the point of collapse I can't really see two straps doing much harm. It's only 16 feet long, not a supertanker.

 

[SwedishLass]

If you are concerned about the strength of the ribs etc is to manoeuvre the boat plus trailer into its working area and using jacks under the keel, blocks (often the ubiquitous oil drums or kegs) and wedges working from the stern lift and support move the trailer forward as far as it will go and repeat. Seen it done with boats up to 34ft.

Alternative is 2 bits of box section (big enough go over forks) with hooks at each end (wider than the boat) and broad strops. Rough guide space strops 1/3 of length fore & aft.

Joann is regularly lifted on 2 strops, weighs 2 tonnes plus usual extras, Trailer purpose built with lifting frame. four chain blocks. the key is not to have strops going to central point so that the crushing is much reduced.

The image Click for picture shows her in the club hoist but the triangular strengthener by the hoist wheels is for one of the sockets which hold a goalpost type frame on each side, four chain blocks do the business at antifouling time.

 

[akirk]

Thank you for some great advice, a lot to think about!

The boat is pretty solid, so not about to fall to pieces with the slightest pressure, however, not worth taking any risks either...

It seems that I have two options:
- a modified version of Grahame's suggestion - use the farm machinery to lift her up, wheel trailer out, lower gently onto supports...

- some form of strops (spaced apart as per LakeSailor's diagram which makes a lot of sense - thank you - so that there is less pressure on the hull, and preferably using more than two ropes - i.e. wider straps / multiple straps etc.

the second is theoretically preferable as it makes it a lot easier to move the boat if it is in the way for the farmer - lift and then trundle off and put back down... the first requires the trailer to be used each time we want to shift it...

I will pop over there tonight and see if I can look at the machinery (no idea what it is called!), to measure up / see what makes sense...

one other thought - if not using rope, but straps instead, how would you construct it / where would you buy the straps / bits? I can imagine that it is one of those times when the components would be cheap, but buying it as a set could be expensive...

 

[SwedishLass]

I purchased a pair of lifting strops from machine mart...other suppliers are available link As for the rest your farmer may have a large useful box of bits and a welder. Out of curiosity how was it put on the trailer in the first place as orig photo appeared to be on rollers. As the manuals say refitting is the reverse process.

 

[Lakesailor]

Let us know the outcome.

 

[akirk]

Thank you all for the helpful suggestions - Grahame, we put it on the trailer with a lot of muscle power, a car jack, some rollers, and jumping on one end of the trailer to lower it below the boat! The trailer also has a winch.

Mainly my concern is to be able to lift it whenever we want without it being too much effort...

 

[akirk]

Okay - a possible change in thought process /forums/images/graemlins/smile.gif

A suggestion from a friend:

the barn is built from a girder structure and the girders are lets say c. 12 foot apart (not measured precisely).

if I were to put on a hoist / winch system (attaching to two sets of the girders), then the boat would be lifted on a bed of strops and there would be no danger of crushing the hull...

so some questions:

- would you run the supports from the girders down under the boat so that they provided a gentle supporting net structure?
- would you run something from one beam across to the other, and then the supports from that?
- I am assuming that I will need 4 points to attach on the beams, two ends & two sides of the boat = 4
- however not sure that I want to buy 4 x hoists, so how do I do it? Looking at machine mart (thank you Grahame), they do offer girder clamps, so presumably I could use these on one girder as anchors, and then two hoists on the other?
- If I do this, will the boat be lifted only from one side and therefore roll?

- any thoughts or suggestions would be very welcome.

I like the idea of doing this, esp. if the attachments to the beams easily clamp on and off as I can then move them down to the next set of girders when I lift my motor cruiser from the Thames this winter and use them there to lift her to paint / antifoul the hull...

 

[Sixpence]

Don't know if it helps but when Miss Ellie ( 21 ft plywood Debutante ) arrived here she was on a borrowed trailer and had to be moved to my trailer . A farmer loaned me a teleporter ( bale lifter , not star trek ) and she was just lifted straight up using two straps carefully adjusted to avoid any fore / aft tilt . and a couple of sturdy beams as spreaders across the fore and aft decks . Now I may be a bit thick but I think you'll find I was more at risk with her being an old 21 ft that had some rot , than a sturdier sounding 16 ft . Personally I would just go for it , but take the time to get the straps in the right position , lift her a little and if she tilts , put her down and adjust . Good luck but I think you may be fretting overly

 

[Lakesailor]

...........and take pictures.

 

[akirk]

Trevera25, thank you that gives me some confidence /forums/images/graemlins/smile.gif

LakeSailor - will do - you can't separate me from my camera!

 

[Johnnie38]

If you take a look at the wooden boat forums, don danenbergs forums (www.danenberg.com) and the chris craft antique boat forums and search on the terms "rolling"a boat and "flipping" a boat - you'll find lots of ideas. The ref below show several pictures of various indoor rigs to achieve this. One thing no-one has mentioned is bracing the boat internally with wooden struts - to counteract the crushing forces which have been mentioned.

http://www.chris-craft.org/discussion/vi...4059daa12162480

Regards
John

 

[akirk]

Thank you, that is very useful... and the idea of bracing internally is a good one, well, aiming to do it soon, so will take some photos and let people know what happens...