Boat fall tragedy in Weymouth

[lpdsn]

What if it's pouring at the time you have booked a lift in?

I confess I try to check the weather forecast in advance but I have ended up anti-fouling in the rain before.

 

[Norman_E]

I must confess that I don't really like metal cradles and prefer the way my marina in Marmaris props boats on multiple wooden props then cross braces them with battens nailed on diagonally both fore and aft and crosswise beneath the hull. The only year that I had a cradle instead I regretted it because of the vibration felt inside the boat whenever the wind blew. I actually got the yard men to add some wooden props to damp the vibration. Whilst that boat weighs less than a third of mine it looks to me as if that cradle is quite lightly constructed. I have seen the heavyweight cradles used in Marmaris have one pad at a time lowered to paint under it, but when that is done a wooden prop is added nearby with wooden wedges driven in to take the load. With any cradle providing four point support with the boat largely resting its weight on the keel it is almost inevitable that the boat will not only be leaning a bit more of its mass on one side than the other, but that one of the props on each side will be taking more of any sideways load than the other. Release the wrong one and the other may well bend and give way, and the same would happen if a weld gave way on one prop. All that prevents tragedy with a cradle like that is some fairly small section diagonal braces and the welds holding then. The failure of just one small weld could cause collapse.

 

[Spyro]

I confess I try to check the weather forecast in advance but I have ended up anti-fouling in the rain before.

Sadly the forecast 3 weeks in advance is not that good, that's about the lead time on getting a booking this time of year where I am

 

[Graham376]

I don't like wooden props. The steel frames we are in are heavy duty with 8 Acrow props and pads plus 4 tie down webbing straps from fore and aft cleats to bolts in the concrete. Usual practice is to drop 4 props (2 each side) at a time when antifouling.

 

[LittleSister]

I agree with your conclusion that the props are best high up . . .

But that was not my conclusion!

 

[JumbleDuck]

I agree with your conclusion that the props are best high up ...

But that was not my conclusion!

Ideally, also, the pads would be as high up the side of the boat as possible.

 

[Seajet]

Unlike a lot of people, my first thought about the tragedy in Weymouth was ' maybe a cradle leg folded ' - I can't see how lowering a pad a few inches, which is all that's required to get a paint brush in, should cause a boat to topple even allowing for skewing forces such as wind on hull and rig - I do agree I'd have had the foresail off, but I suppose this was an ' out for a quick antifoul ' job so can understand the temptation to leave it on.

By all accounts the victim was experienced and a good seaman, there was a comment about him leaving the lines immaculately coiled on a boat he'd been alongside earlier; I know people who fancy themselves as red hot racers I've sailed thousands of miles with who wouldn't bother to do that, sounds to me like the sailing world has lost a good one.

 

[lpdsn]

Sadly the forecast 3 weeks in advance is not that good, that's about the lead time on getting a booking this time of year where I am

Ok, I'm luckier there. After one year when I had to reverse in with a F6 on the nose and no way to fender off the hoist dock I've always checked the forecast then phoned them up a day or two before to avoid putting myself in a similar situation. It often means taking a day off and avoiding requesting a saturday morning

 

[lpdsn]

Unlike a lot of people, my first thought about the tragedy in Weymouth was ' maybe a cradle leg folded ' - I can't see how lowering a pad a few inches, which is all that's required to get a paint brush in, should cause a boat to topple even allowing for skewing forces such as wind on hull and rig - I do agree I'd have had the foresail off, but I suppose this was an ' out for a quick antifoul ' job so can understand the temptation to leave it on.

By all accounts the victim was experienced and a good seaman, there was a comment about him leaving the lines immaculately coiled on a boat he'd been alongside earlier; I know people who fancy themselves as red hot racers I've sailed thousands of miles with who wouldn't bother to do that, sounds to me like the sailing world has lost a good one.

I agree with you.

Although it has also been said it was his first boat and by implication first anti-foul.

 

[LittleSister]

I agree with your conclusion that the props are best high up,

But that was not my conclusion!

. . . Therefore, as I see it, the props should ideally be in line with an arc centred on the base of the keel, so that the force on the prop is compressing it along its length, not trying to bend it.

Ideally, also, the pads would be as high up the side of the boat as possible.

In practice the combination of the two would require a very wide base for the cradle, and take more room than the average boatyard or club would be willing to tolerate, therefore a degree of compromise is required.

Having the pads up as high as possible as the sole criterion will mean the struts will be subject to lateral loads, and at risk of bending, rather than compressive loads which they are best able to resist. . . .

 

[lpdsn]

Having the pads up as high as possible as the sole criterion will mean the struts will be subject to lateral loads, and at risk of bending, rather than compressive loads which they are best able to resist. . . .

The risk of bending will depend upon the lateral forces involved. How big do you think they are?

 

[DJE]

I don't like wooden props. The steel frames we are in are heavy duty with 8 Acrow props and pads plus 4 tie down webbing straps from fore and aft cleats to bolts in the concrete. Usual practice is to drop 4 props (2 each side) at a time when antifouling.

There are good and bad wooden props just as there are good and bad steel cradles.

 

[savageseadog]

Having the pads up as high as possible as the sole criterion will mean the struts will be subject to lateral loads, and at risk of bending, rather than compressive loads which they are best able to resist. . . .

The cradle must primarily hold the boat upright, lateral support is most important. The deadweight of the boat is best kept off the cradle, other forces will also be largely lateral due to the windage. For the cradle to have a reasonable footprint the supporting arms have to be at some angle from the horizontal and both a vertical and horizontal forces act on them. The supports must therefore be able to resist bending forces, to that end the arms are made strong enough, hopefully and will have cross bracing.

 

[AntarcticPilot]

I have seen people drop a prop to antifoul under a pad, put a plastic bag over the pad and replace the prop within minutes.
You can usually get away with it on long keelers, and I have seen people do it on fin keelers.

However no boatyard would allow you to do this, and I wouldn't dream of removing any support, on any boat without adding a replacement.
I used to use an oil drum and wooden wedges, but about 7 years ago I bought a large single boat prop. It's paid for itself with the number of pints I get bought for lending it out.
As a self help club we have guidelines that are expected to be followed. Not just for safety but consideration of other club members.
This includes moorings, antifouling, and for those with steel boats grinding.

The last time Capricious was out of the water for a prolonged period was when I did the Coppercoat. The marina concerned (James Watt Dock) has strict rules about using cradles (good steel ones, far stronger than the one in the photos) for boats out of the water. As Coppercoat requires several days to reach load bearing strength and resistance to water, obviously simply dropping a pad and then replacing it wasn't an option, nor was doing under the pads while the boat was in slings. The marina insisted on handling ALL changes of propping, and replaced the cradle pads with Acro-props when I was ready to do the areas under the cradle pads. These were cross-braced, and the cradle props replaced as soon as the Coppercoat was load-bearing. I would regard all this as being good practice, and felt completely safe working on and around the boat (I was sleeping aboard her!). I don't recall them charging for handling the change of props, so either they didn't or it was a small charge compared withthe rest of the bill!

You can still slap some antifoul on. I usually book a lift in around lunchtime, so the guys bring the boatlift round before lunch, lift and hold in the slings, go to lunch. I get an hour to pop a couple of coats of antifoul on the pad patches. Then they come back and drop the boat in the water.

Both marinas I've been in in Scotland would antifoul under pads etc. on launching if you left them a tin of the relevant antifoul on launch date (usually the tail end of a tin)! This was routine, matter-of-course stuff, for which no additional charge was made. However, it was also the case that neither marina allowed untrained personnel near the boat while it was being lifted and moved.

 

[LittleSister]

The cradle must primarily hold the boat upright, lateral support is most important.
I agree

The deadweight of the boat is best kept off the cradle,
I agree

other forces will also be largely lateral due to the windage.
The forces on the boat will be (largely) lateral, but the weight (of the sort of boat we are concerned with) will pin its keel to the ground (in all but a hurricane). Therefore the wind will be tipping/rolling the boat laterally around the point where the keel meets the ground: it is effectively a pivot.

So the bit of the hull against the pad will not move purely sideways: unsupported it will move downwards and outwards in a curve which is part of a circle centred on the keel/ground 'pivot'. Then supports would ideally be aligned with that curve (all other things being equal).


For the cradle to have a reasonable footprint the supporting arms have to be at some angle from the horizontal and both a vertical and horizontal forces act on them.
I agree, for the reasons stated above.

The supports must therefore be able to resist bending forces,
I disagree in that I consider they should be set up to avoid bending forces as much as practicable: the supports should be taking the forces primarily in compression.

They obviously must be able to resist some bending forces, but they will be less resistant to those than to compression. There will be minor elements of bending force a) to resist the boat twisting (yawing) about the keel, and (b) to compensate for the support base usually being narrower (for space saving reasons) than ideal for purely support purposes, which results in the pads being lower than ideal.


to that end the arms are made strong enough, hopefully and will have cross bracing.
I agree that supports should be made strong enough and have cross bracing!

 

[Dipper]

The man who died has been named by the local paper as Kevin Keeler, 56. He had been a keen sailor since he was a teenager so it is likely that some on these forums knew him.

 

[alant]

Unlike a lot of people, my first thought about the tragedy in Weymouth was ' maybe a cradle leg folded ' - I can't see how lowering a pad a few inches, which is all that's required to get a paint brush in, should cause a boat to topple even allowing for skewing forces such as wind on hull and rig - I do agree I'd have had the foresail off, but I suppose this was an ' out for a quick antifoul ' job so can understand the temptation to leave it on.

By all accounts the victim was experienced and a good seaman, there was a comment about him leaving the lines immaculately coiled on a boat he'd been alongside earlier; I know people who fancy themselves as red hot racers I've sailed thousands of miles with who wouldn't bother to do that, sounds to me like the sailing world has lost a good one.

What has "a good seaman" got to do with his boat falling over?

 

[westhinder]

I don't like wooden props. The steel frames we are in are heavy duty with 8 Acrow props and pads plus 4 tie down webbing straps from fore and aft cleats to bolts in the concrete. Usual practice is to drop 4 props (2 each side) at a time when antifouling.

I must say I have always been amazed at the number of boats in U.K. boatyards supported by wooden props. To me they seem inherently unsafe, I would never trust them.
Where I live, all boatyards use steel cradles, most of which are sturdy enough, although sometimes heavy storms will topple boats, so not all cradles are ok or are checked thoroughly enough.

 

[JumbleDuck]

Having the pads up as high as possible as the sole criterion will mean the struts will be subject to lateral loads, and at risk of bending, rather than compressive loads which they are best able to resist. . . .

But the higher up they are, the lower the loads will be. Bucking failure in compression is a bigger problem than bending failure, normally. Your arc theory is elegant but doesn't reflect the actual forces.

 

[rogerthebodger]

To keep a boat upright does not need a great deal of support. VyV has used boat legs to keep his boat upright in a tidal harbour.

I have a 24 ton boat supported on wood poles the diameter of a wooden telegraph pole but I have at least 8 each side so much redundancy.

In this case there was little of no redundancy and the for /aft and sideways braces are small and only go half way up the support leg.

It looks like to for starboard side failed and I would like to see a pic of that to see how it failed.

A slender column in compression will not need much sideways load to start a compression failure.

This is a pic of my 13 ton boat on its truck with only 3 supports each side moved 1200 Km like that. I moved another boat 24 ton an a similar truck with 8 struts each side but with a lot of bracing on a 800 Km trip.

finish now 20 ton

The bracing on on both those cradles in my view is totally inadequate even for a smallish boat like that.

This is the cradle I used when fitting my boat above

Note the bracing and how high it goes up to the supports.