A Frame - For Mast Lowering

[Lakesailor]

Yes, thanks I had been in touch with Neil Thompson but he wanted a staggering £1200 for the mast lowering equipment. It is a permanent fixture that replaces the pulpit. Hence my attempts at DIY.

Staggering indeed.
Your idea of having the cross bar which rotates as you lift the mast. I'm not quite sure what the purpose of that is. It will be well forward and below the pivot of the mast in the tabernacle.
Much better to have a gin pole with a saddle which locates on the mast pivot bolt. This will also help stabilise the mast.

The hinge in the side plate (yes I know there are two, only one works - this was my prototype) allows you to locate the plates over the ends of the pivot pin before screwing the nut back on. You need a pivot pin with a thread and a nut at each end for this method to work so that you can attach the pole without removing the pivot.

 

[viva]

What a great idea. What is on the other end please?

 

[oldbilbo]

Raising and lowering heavy spars has been a shipboard routine since Noah's time.... and is still a regular requirement, as seen above. It is often over-complicated.

The first requirement is a sheer ( or 'shear' ) legs - which is the A-frame. That is adequately and easily/cheaply joined close to the apex by a sheer lashing - http://www.animatedknots.com/lashshear/index.php?LogoImage=LogoGrog.jpg&Website=www.animatedknots.com See also Google Images for examples of 'sheer legs' in use.

This is an arrangement that many thousands of Boy Sprouts learned to do at Easter Camps around the world, just a few short decades ago. I used a pair of 16' aluminium sailboard masts for a 31' aluminium spar, and these were perfectly adequate. When the two legs are splayed apart, the lashing is tightened.

The lower ends/heels of these were positioned on the side decks in line with the mast pivot, just inside the toerails, and secured from fore-aft-sideways movement with cords. Concern that the GRP deck surface would be damaged was assuaged by fitting the heels into 'shoes' made from sections of heavy-gauge exhaust tube with a circular hole cut in one wall.

The sheerlegs were mounted, initially, with the apex leaning on/over the pulpit. A masthead halyard was secured to the sheerlegs apex, and another 'controlling' rope from the same apex/point around a cleat on the pontoon walkway a few feet ahead of the bow.

A shorter sheerlegs was mounted at the stern, lashed to the rails of the pushpit, to receive the lowered mast. Two further halyards were held by helpers standing on finger pontoons out to port/starboard in case of need to control any lateral 'lean', but they proved unecessary.

The forestay was eased/disconnected and the 'controlling rope' eased away around the pontoon cleat ( by Sara of this parish ). As the mast leaned further and further aft, the sheerlegs - secured by the first halyard - rose up, taking the load progressively.

No-one was stood under the mast at any time, and the lowering was conducted in perfect control.... much to the surprise and chagrin of the Dover Marina dockies, who'd been betting on a calamitous collapse! That saved some £115 + VAT for the hire of the dockies' crane....

So, 'build in simplicity and add lightness', in Colin Chapman's famous dictum.

 

[Lakesailor]

What a great idea. What is on the other end please?

A tab on the pole which I bolted to the forestay s/s strip. Then take the clevis pin from the bottom so the furling gear is actually fixed to the gin pole. The loop on the end of the pole is to attach the line which runs under the bow roller and off to the winch I used to control the lowering.

It cost me exactly nothing. I had bits of pipe and steel laying about and have a stick welder. The pipe was galvanised so the welds were a bit splattery, I couldn't be arsed to grind the coating off

 

[Simon_blackburn]

I have read all this with great interest and now have a much better understanding of the ways in which people step masts. I was recommended to go the fixed a-frame route (using the A frame as a crane - Albin Vega style) from a fellow Shipman 28 owner in Denmark and cannot really see a downside: I'm only going to be taking the mast down/up as part of laying up.

Presumably the gin pole or pivoting A-frame only works where your mast tabernacle has a pivot, otherwise all that pressure would cause the foot of the mast to skid all over the place when it came out of its cup, whereas in the 'crane' scenario, the pivoting and lifting goes on round the spreaders and you only need to guide the foot of the mast as the whole lot comes down.

I still have a few months to dream something up but I'm leaning towards the A-Frame crane at the moment.

 

[Slowboat35]

If you are lowering the mast using the bow roller as your front pulley, then the ideal length for the A frame is exactly the length from the mast foot to the bow roller.

Which, conveniently, is the same length as your spinnaker pole.
An alternative to A frames is to insert a 4 way tackle between the forestay and bow fitting (use the spinny halyard to support the mast temporarily in it's stead) and run the tackle's tail back to a cockpit winch. The pole can be stayed laterally if possible, or use the shrouds if geometry allows and as the forestay is fixed the pole remains at right angles to the mast acting as a derrick. The last few degrees - and first few on raising by the same method) are often assisted by hand from the cockpit or coachroof.
Thought needs to be given to the changing relative axes and geometry of of the tabernacle and shroud attachment points, some fittings may need ot be fabricay=ted but with the ger in hand this allows most masts to be raied and lowered by just two people.
The wincher needs to very alert and be protected from the mast should anything give way...

 

[neil_s]

On an 8 ton Hilliard with a mast approximately 33 feet long, I used an A frame with legs about 8 feet long. The length was chosen so that the feet of the A frame could rest (with suitable padding) against the coach roof front and the top aligned with the windlass on the fore deck. I had a strong tabernacle so no lateral support for the mast was needed.

 

[Laminar Flow]

The Dutch boats do this quite frequently and expediently, even shooting bridges and on some rather large boats as well.
Many have a permanently installed A-frame that folds down along the gunnels from the mast to the bows.
On many boats, traditional and not, the anchor winch is used in conjunction with the frame to lower the mast. The rest is simple physics.

For a temporary solution, you could pick up a couple of scaffolding poles and brackets.

 

[rogerthebodger]

Lots of info on mast lowering

mast lowering on the swan river site:forums.ybw.com - Google Search

 

[William_H]

Nice video Roger. Yes I have seen Syrenca go past our club at times. (seen at 56 seconds) That is one enormous mast. Needless to say a harrowing experience when mobos come past causing rocking. As I have said before best to have a crutch at the stern to catch the mast which is as high as possible commensurate with getting under the bridges or that you can reach to lower mast after removing from tabernale. (higher crutch means less hoisting to get it back up) ol'will

 

[rogerthebodger]

Nice video Roger. Yes I have seen Syrenca go past our club at times. (seen at 56 seconds) That is one enormous mast. Needless to say a harrowing experience when mobos come past causing rocking. As I have said before best to have a crutch at the stern to catch the mast which is as high as possible commensurate with getting under the bridges or that you can reach to lower mast after removing from tabernale. (higher crutch means less hoisting to get it back up) ol'will

Thanks

I was last in Freo in 2001 on my way to Melbourn for the F1 GP.

Took Captain Cook several times from Freo to Perth several times but did not know of visit and of the Yacht Clubs. If we do vere visit again will certainlly visit EFYC.

Visited Sydney during the same trip but no sailing, just did some diving on Heron Island.