Raising boat off trailer for anti-fouling

[NigelCraig]

Earlier this year, I did a very good job of anti-fouling my trailer! This time, I want to lift the boat (Cornish Crabber 17) a bit up off its trailer, to get at the bits that sit on the trailer supports. The keel sits on rollers along most of its length and there are supports under the bilge strakes.

Just looking for suggestions/techniques on how to raise it enough to got antifouling onto the bit normally in contact with the trailer? Not sure what the boat weighs - displacement is 657kg.

 

[Rigger Mortice]

I've just done this on my boat so that I can do some work on the keel.
I jacked the boat and trailer up, put two wooden beams under her, with the ends on pillars of concrete blocks. The boat also has legs, so those were fitted and propped up on two more pillars of concrete blocks. Everything wedged up tight. Then lower the trailer and bob is the proverbial. It all went surprisingly well and I was quite pleased with myself for doing it without a hitch. The boat is now sitting on the beams and I simply pull the trailer out when I want to get at the keel.

BUT, thats a lot of effort if you just want to antifoul. Can't you lower one support at a time? Lower support, antifoul, raise support. Repeat on next support.
Then move the boat on the rollers (making sure that the trailer is firmly supported all round) Antifoul. Move boat back.
It's all a bit fiddly, but a lot easier than lifting the whole boat.

 

[capetown]

Hi and welcome,

You might be able to jack one side, then pack with wood and carpet just enough to antifoul, then the same for the other, chocking the trailer first.

Or the same but forward then aft.

I used a trolley jack to lift the the aft of my Sonata, then slid a steel bench under with shaped wood and carpet, same for the pointy end, as I needed to remove the centerboard.

With care and plenty of old carpet, the trick is not to rush it, just think what could happen say, if it fell off the jack or if the jack gave up, as long as you spread the load and build up your packing as you go, then if it goes pearshape, there's nowhere for it to go.

Ps, Could also consider a scaffold plank as a lever?

 

[VicS]

Not sure what the boat weighs - displacement is 657kg.

The displacement is the weight ! Although the quoted figure does not include all the extra junk you have put onboard .. just the basic boat.

Remember learning about that old Greek guy ... Archimedes .. not Phil the Greek ... who yelled, "Eureka" when he worked out why his bath overflowed when he got in it

 

[SimonD]

I would have agreed with Vic until recently (and usually, he's quite right of course). However, there can be a wrinkle. My boat is quoted with a Displacement to DWL (Design Waterline). This means the weight of the boat loaded with people, stores etc. so that it floats to its intended waterline. Also quoted is the "Trailing Weight". This the weight of the "empty" boat, sitting on it's trailer. There is a 200kg difference between the two weights!

Back to the question, the suggestions look sensible. In addition, I understand that some boats, particularly those on a breakback trailer, can be "launched" onto dry land. If so, maybe you could then careen the boat to paint one side, then the other. Saves any worry of having it up in the air.

 

[NigelCraig]

I would have agreed with Vic until recently (and usually, he's quite right of course). However, there can be a wrinkle. My boat is quoted with a Displacement to DWL (Design Waterline). This means the weight of the boat loaded with people, stores etc. so that it floats to its intended waterline. Also quoted is the "Trailing Weight". This the weight of the "empty" boat, sitting on it's trailer. There is a 200kg difference between the two weights!

Back to the question, the suggestions look sensible. In addition, I understand that some boats, particularly those on a breakback trailer, can be "launched" onto dry land. If so, maybe you could then careen the boat to paint one side, then the other. Saves any worry of having it up in the air.

It is a breakback trailer but I don't know if it "breaks" as i've never used it - however it's in a farmers shed so haven't got room to do that anyway.

I like the suggestion of dropping each side support in turn - presumably would need to prop up beforehand. Moving fore and aft along the trailer sounds more tricky. I wonder if I could use a bottle jack under the rudder skeg to jack up the stern before sticking a wooden wedge in or would that bend the (steel) skeg as a large part of the weight of the boat would be on it. Difficult to jack up other end as the spine of the trailer gets in the way.

 

[Rigger Mortice]

I like the suggestion of dropping each side support in turn - presumably would need to prop up beforehand.

Props may not be needed at all. I used to be concerned about it, as you are. Then I noticed that I could see daylight between the boat and one of the support pads, so it was obviously not bearing any weight. So I lowered it, antifouled, and then raised it tight up to the boat.

I think the side supports are mainly needed when the boat is underway on the trailer.

I am now quite relaxed about lowering the pads a few inches so that I can get the antifoul on. I don't think that I would go jumping around on the side decks, but there has never been any sign of movement. Always one at a time.

It may be OK on your setup too but it's obviously wise to err on the side of caution.

Personally, I would be cautious about putting too much load on a skeg but I don't know what you boat is like below the waterline. If she sits on the skeg when drying out then you can probably do it.

 

[VicS]

It is a breakback trailer but I don't know if it "breaks" as i've never used it - however it's in a farmers shed so haven't got room to do that anyway.

I like the suggestion of dropping each side support in turn - presumably would need to prop up beforehand. Moving fore and aft along the trailer sounds more tricky. I wonder if I could use a bottle jack under the rudder skeg to jack up the stern before sticking a wooden wedge in or would that bend the (steel) skeg as a large part of the weight of the boat would be on it. Difficult to jack up other end as the spine of the trailer gets in the way.

I think I would be nervous about putting a lot of weight on that part you refer to as a skeg . Shown in the fifth picture in this SLIDE SHOW. But it appears to have a sturdy support to the bottom of the transom and it must be strong enough to take a pounding in the event of the boat going aground. Pad it well with a solid piece of wood to spread the load between the end of the keel and the post at the aft end and I think it will be OK. Dont just stick a jack under the centre of it.

BTW I take it you are antifouling because you intend to keep the boat afloat. Unnecessary if all you are doing is trailer-sailing!

 

[jellylegs]

I've painted one of these. Just drop the side supports a couple of inches and rock her side to side. With regard to the keel, just roll her backwards on the trailer a little and you can fill in the missed bits. When dry pull her forward again.

Re the displacement, it has to be a greater displacement than the weight otherwise she will sink, as I understand it.

 

[VicS]

Re the displacement, it has to be a greater displacement than the weight otherwise she will sink, as I understand it.

When the boat is floating the weight of water displaced is equal to the weight of the boat! Basic school-boy physics

Only one figure quoted by the way for the Crabber 17 (no "trailing weight")

 

[NigelCraig]

I think I would be nervous about putting a lot of weight on that part you refer to as a skeg . Shown in the fifth picture in this SLIDE SHOW. But it appears to have a sturdy support to the bottom of the transom and it must be strong enough to take a pounding in the event of the boat going aground. Pad it well with a solid piece of wood to spread the load between the end of the keel and the post at the aft end and I think it will be OK. Dont just stick a jack under the centre of it.

BTW I take it you are antifouling because you intend to keep the boat afloat. Unnecessary if all you are doing is trailer-sailing!

Er, yes! Drying mooring (trots) in Lyme Regis harbour April to September

 

[VicS]

Er, yes! Drying mooring (trots) in Lyme Regis harbour April to September

Fair enough! I expect you'll need some good antifouling there!

 

[William_H]

A/F painting ona trailer

I do this every winter.
I find I can push the boat back on its rollers by about 1.5 ft. I need jack and blocks under the back of the trailer frame as it tips up without. This gives me more of stern clear for painting. I can lower the front to raise the stern to give more room.
I jack the whole trailer to give more room for me to lie underneath. When the boat is back on the trailer it exposes the keel slot so I can drop that down to paint. (bottom half).
A friend built a huge gantry with chain blocks and webbing to lift his fin keel off its trailer. I borrowed this once but really it was too much trouble so I am back to sliding underneath.
Of course when the paint is hard I winch the boat back into position so exposing areas not painted.
Yes it is a pain but being at home I can take my time. good luck and be careful olewill

 

[William_H]

Painting boat on trailer

Just a little more to add to the above. You can drop the tow hitch of the trailer down to the ground then fit under the stern of the boat a stout trestle. Now when you jack up the tow hitch the stern will be lifted by the trestle while the front of the boat is lifted and supported by the trailer. You may then have room to paint under rollers etc. But again be careful olewill

 

[jellylegs]

When the boat is floating the weight of water displaced is equal to the weight of the boat! Basic school-boy physics

Only one figure quoted by the way for the Crabber 17 (no "trailing weight")

I am basic, and not far from being a school boy!

 

[SimonD]

Er, yes! Drying mooring (trots) in Lyme Regis harbour April to September

I got excited about following your example, until I checked the website: a waiting list of 100! How long did it take you to get a mooring?

 

[ProDave]

I antifoul my boat on it's trailer. I drop the supports one at a time to paint under them.

that leaves just a few keel rollers where I can't paint under.

I don't fancy any of the jack up techniques as that would place all the load on 1 or 2 points, rather than spread out over several rollers.

An alternative might be to try and winch the boat forwards or backwards on the trailer to expose those few parts?

However, here's the point of my posting and a question:

My boat spends it's summer in a drying harbour. On lift out, most of the hull was clean, but the very bottom, that sits in the mud twice a day, had a good crop of tiny barnacles.

I can only assume the part that sits on the mud, the antifoul had rubbed off?

So either I used the wrong antifoul, or this is something to be expected on a drying mooring?

If that's just to be expected, then missing a few little patches does not sound to be much of an issue.

 

[William_H]

A/F on the bottom

No one else seems to have commented on the barnacles growing on the bottom.
I have no real experience as to why. When you come to clean the bottom you will get an idea if the a/f has been rubbed off by the mud. I imagine it would be quite abrasive as she settles. All you can do is add more A/F and make sure what you buy is a hard (racing) A/F not a self ablating type as many are.
The barnacles may be surviving on the bottom because that is the part that stays damp. olewill

 

[Lakesailor]

I can attest to the stability of boats about the vertical position. When I collected Slippy ( a fin keel Foxcub) on the drive back from Coniston I noticed in the driving mirror that she was leaning. I stopped and discovered the prop at one side had come loose and had leaned away from the boat, only being prevented from falling right over by the steel mudguard. The boat was leaning at about 20°.
The bloke I had just bought it from arrived (by chance) and we used strops to the remaining post on the other side to prevent any further movement. Pinched a nut and bolt from the jockey wheel bracket and set about pushing the boat upright to fit the bolt into the prop again. Two of us easily managed to push the boat vertical again. One person could have done it.

 

[Zagato]

That's a worrying pic Lakesailer but shows how strong the hull is

A friend of mine simply back winches his Drascombe Coaster onto chocks for maintenance.

At some point I will have to replace the keel rubbing strip, I suppose this will really need jacking up for that, weighs 1000KG