Small boat mast climb?

Colin24

Colin24

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I’m thinking of buying a mast ladder, I’ve had a look round the net and think the ‘Deffee’ type would be best for me.

My question is, how feasible is climbing my mast with regard to stability.

I weigh 185 lbs

Boat figures are:

LOA 23’ 6”
LWL 18’ 6”
Beam 8’ 9”
Draft 3’ 3”

Displacement 4,400 lbs
Ballast 1,800 lbs

Rating LBSA TCF 6496

Bilge keels

Mast Height from cabin top 27’ 6”
Cabin top to waterline. 5’

The Deffee Ladder stays fixed close to the mast, rather than swinging around.
I would be climbing in still water with the boat alongside a sheltered pontoon.

Given the above would it be

A. foolish to attempt, will end up swaying about ending with a crash landing on neighboring boats.
B. Doable, but a bit dodgy.
C. No problem, go for it.
 
I have a Deffee for my 9m mast on a sadler 26.

I've tried the bosun's chair and caving ladder options but the Deffee which locks into the mast track is very much better for me.

I can get up and down easily, I weigh 77kgs and past the first flush of youth. It matters not one bit whether the boat is chocked up on land or afloat as it remains stable and I can work at the masthead safely ( my boat is 2000kg displacement and fin keel if that is of any interest).

The ladder wraps up in its netting bag to about the size of a 3 season sleeping bag but weighs a good bit more than that of course- so stowage space needs to be considered too
 
That’s encouraging, I have been told it’s quite a heavy boat for it’s size. I’d have thought that would be to my advantage for this task.
 
Since the weight is supported vertically I can't see it matters either way what the weight is- if you were to set up a pendulum( which you won't) it would very likely matter then!.

I forget what mine weighs but it is about the same length that you need and I can heft it in one hand, so probably about 5-7 kgs only- I reckon its much lighter than my outboard which weighs 12-13 kgs.

I tried to get a test climb before shelling out a couple of hundred quid but there was nobody local to me so in the end I just went for it and my first climb was in a gusty F5 in the yard.

At first I was nervous of tipping the boat even when chocked and the gusts didn't exactly help but it all went well and I was up and down several more times without any qualms.

By the way, if anyone is around then I get them to top rope me in case I slip but since this device is really useful singlehanded I always wear a full riggers harness (which grips the thighs a bit) and a fall arrest lanyard and arrester so that if I do fall I don't hit the deck nor end up hanging upside down. The full harness cost about £34 from screwfix but the Petzl ASAP fall arrester is very, very expensive at £100 but then what's a life worth?
 
Mines
LOA 23 ft
LWL 19'10"
Draft 2'9"
Beam 8'"4
Displacement 4400 lbs
Ballast 2200 lbs

When my forestay need replacing, under guarantee, the rigger sent his 'lad' up the mast using a mast ladder, plus him on the safety line and me acting as movable ballast to keep the boat upright. He also used ropes to help stop the boat tipping by tying it to the pontoon and the adjascent boat. A Virg is a bit tender.
He did say that normally he would never send anyone up the mast on anything less than 8 metres, but as he would have had to pay for the mast lift, and the day was fairly still, he would use the mast ladder. There was just one point that caused the lad to wonder what he was doing up there. The boat started tipping and we had to move pretty nimbly to keep the mast vertical.
 
If you take the top of the mast as 27.5 + 5 = 32.5 ft above the water and your weight as 185 lbs that gives a poential tuning moment of 32.5 x 185= 6012.5 lbs feet.

Take the righting moment as the ballast x the depth to the centre of the keels (say about 2.25 feet) you get 1800 x2.25 = 4050 lbs feet.

That means that your weight at the top of the mast has a greater potential to capsize the boat than the keels have to right it.

OK that ignores factors such as the hull weight and the beam but until someone can produce some calculations to prove otherwise I would say you are looking at an unstable situation if you venture more than about 2/3 of the way up the mast (measured from the waterline). So unless someone can prove it is safe don't do it unless the boat is on shore or has its keels firmmly imbedded in a muddy bottom.
 
Climbing the mast is a fairly common ocurrence. Does anyone have any first hand experience of such an operation causing a capsize?
 
VicS, why did you exclude the weight of the boat? I think the keels are only a part of the righting force. If you take the weight of the boat, acting at the centre of gravity, presumably at least a foot or so below the centre of bouancy then you have a righting force of 1' x 4,400lbs, plus say 1,000lbs of gear gets you much closer to 5,400ft-lbs.

Having said all that I must admit I tend to go up the mast (on a couple of halyards) only when hard aground! Mainly because I don't like all that wobbling around magnified by the mast length!
 
Easiest way to know if you will pull the boat over is to stand on the pontoon, hold the main halyard above your head and pull down, once you have all your weight on the halyard and the boat won't go over any further then you know it's ok to climb.
I've been to the mast top of my 26 footer and I weigh 14 stone. It does tend to go over to about 10 degrees then stay there depending on what the person on the deck is doing.
On the other hand if you could pull it over then you woudn't have to climb it.
 
There is one very simple way to find out if your stability is OK re having yourself at the top of the mast.
Get a bosun's chair, or some form of harness, put yourself in it, and then attach the main or headsail halyard to the harness or chair.
Take up the slack on the halyard so that the halyard is tight when you are standing up by the mast.
Now 'sit down' and let the harness or the chair take ALL of your weight. Lift your feet off the deck.

As far as the boat is concerned, she thinks that you are now immediately at the mast head, because that is where the halyard turning block is, never mind that you are still suspended 1' above the deck.

You will probably notice the boat becoming a bit more 'tippy' - or not. Experiment a bit. Swing from one side to the other. If things start to go pear shaped, just put your feet back down on the deck / cabin top, and your weight is back at deck level.

There is a similar analogy with a cargo ship picking up a heavy lift item from it's hold. The ship heels as soon as the weight comes on the lifting cable, even though the cargo might only be 2" above the tank top of the ship, way down in the bilges.
The weight does NOT have to be at the top of the crane or derrick (or mast) to cause this heel.
 
Interesting. I've been up Silkie's mast 3 times while afloat (alongside in the marina) and was about to say "no problem" until I did some mental arithmetic similar to VicS.

I'm about 165lbs and Silkie is 3900 with 1700 ballast on 22' LOA 17' LW 7'5" beam and 3'9" draft, long fin keel. She probably carries another 500lbs "essential" cruising gear.

How about a couple of experiments to get a feel for the forces involved? Take a halyard well off to the side and see how far you can heel her over. Or go part way up and start throwing your weight around (not so far to fall!) but make sure your mast won't get tangled in anyone else's rigging if she does start to go over.

As I said, I've done it 3 times without incident but maybe I've just been lucky.

Edit: Should have clicked refresh and read the half dozen posts above this one before posting!
 
Bajansailor has it spot on. When calculating the centre of gravity of a floating craft freely suspended loads are assumed to act at the point from which they are suspended. The critical point is to keep the centre of gravity below the metacentre. The difficlut bit is calculating the position of the metacentre. But Spyro's proposed experiment sounds pretty foolproof to me.
 
Spent half an hour at the top of a Hunter Sonata (lift keel version) mast in a full gale (Sixhaven marina) without falling off. Slightly wobbly but never felt like it was going to flop over.

Turning moments of keel are an important part of the calculation, but you need to consider bouyancy as well - a wide boat will be less inclined to tip than an equivalent narrow one.
 
I'd suspect any yacht that can't take the weight of a person up the mast would have problems with the forces imposed on it with sails up in even moderate wind strenghts.
 
My initial reaction was to agree with you Brendan, but with consideration, I'm not sure the parallels are quite there.... with a person up the mast, the turning moment remains constant as the boat heels, however, with a sail, as the boat heels, the turning moment force reduces from the sail... plus sails create lift as well as a horizontal component of force..... so perhaps not quite so obvious as it might first seem...

regardless, my instinct is that you are probably right anyway....
 
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