Does your cabin fit snug with the mast? Does anyone use wedges? What does the movement do to the structure of the cabin? Any thoughts? There is a gap around where the mast passes through the cabin top, seems to move around a bit. The original owner had wedged some heavey rubber padding in there.
Mast & Cabin Top?
- Thread starter Whit
- Start date
Hi Whit. I use hardwood wedges around the mast inside the metal collar that goes through the cabintop. I simply center it with the wedges when I step the mast and tap the wedges tight (flat side against the mast) with a hammer.
You can just cut them out of hardwood. Leave one side flat or 90 degrees to the butt. Cut the wedge or taper on the other side. Mine are about 2" long and around 3/4" thick at the butt. They came with the boat but would be easy to cut more. You certainly want them in as the collar is about and inch larger than the mast.
There's quite alot of stress there. The cabintop is over course doubled to take the side loads from the mast.
With a main bulkhead for and aft of the mast, cabinhouse beam(s) and bronze knee brackets for added strength, they anticipated heavy loads in this area when they designed the boats. I can't say I've seen any movement (or evidence of same) in this area under the conditions we sail in.
You can also pour the Spar tight stuff to form a plug, I've seen problems though in getting them out when upstepping.
You can just cut them out of hardwood. Leave one side flat or 90 degrees to the butt. Cut the wedge or taper on the other side. Mine are about 2" long and around 3/4" thick at the butt. They came with the boat but would be easy to cut more. You certainly want them in as the collar is about and inch larger than the mast.
There's quite alot of stress there. The cabintop is over course doubled to take the side loads from the mast.
With a main bulkhead for and aft of the mast, cabinhouse beam(s) and bronze knee brackets for added strength, they anticipated heavy loads in this area when they designed the boats. I can't say I've seen any movement (or evidence of same) in this area under the conditions we sail in.
You can also pour the Spar tight stuff to form a plug, I've seen problems though in getting them out when upstepping.
“Caravela of Exe” (Caravelle 992J) didn’t come with mast wedges fitted, so I immediately purchased stock Neoprene wedges for fitting all round but found them popping out.
I then followed Rod Stephens’ strict instructions from his chapter on spars and standing rigging in that great book, “Desirable and Undesirable Characteristics of Offshore Yachts” (Ed. John Rousmaniere, Norton, N.Y., 1987) - in which he specifies: “Neoprene mast wedges – fore & aft only”.
By fitting them fore and aft only and cutting a rebate in them so that they hang over the external collar at the thru-house aperture I have had no further problems. A neoprene boot fixed with large hose clamps top and bottom successfully keeps the water out, and one of these days I’ll make a pretty fabric cover for that, to keep U.V. off and make it look nicer.
I then followed Rod Stephens’ strict instructions from his chapter on spars and standing rigging in that great book, “Desirable and Undesirable Characteristics of Offshore Yachts” (Ed. John Rousmaniere, Norton, N.Y., 1987) - in which he specifies: “Neoprene mast wedges – fore & aft only”.
By fitting them fore and aft only and cutting a rebate in them so that they hang over the external collar at the thru-house aperture I have had no further problems. A neoprene boot fixed with large hose clamps top and bottom successfully keeps the water out, and one of these days I’ll make a pretty fabric cover for that, to keep U.V. off and make it look nicer.
I'll have to read Steven's book. I'm quite surprised at his recommendation. Everything else I thought I knew about wedges said 'yes' to side to side and fore and aft. Basically, you are making a far shorter and stiffer column out of the mast when you restrain it. Euler's Law; 'fixed ended' versus 'pin ended' column.
Our North East 38 flexes enough to pop the saloon table support (looks alot like your centerboard cable cover) out of its socket (over 1/2") but she does not spit her wedges. Our Morgan 27 flexed enough, before I tied the deck-mounted chainplates down to the hull, to lift the deck 3/4" or so and spit the wedges. Dad had made special wood wedges with ell-ed tops (so they would not drop out), I replaced them in neoprene. Either way, they had to be restrained in place with an oversized hoseclamp, ugly but effective. This flexure is due to the compression load in the mast, when the rig is loaded, pushing the keel down with respect to the sides of the hull; and the deck either buckles inward or up. I can hear all sorts of movement in the NE 38's cabinetwork when this happens, and watch the table support post move in its socket; I could watch the Morgan's deck lift off the bulkheads. Additionally, the Morgan's forward keel bolt would leak when her rig was loaded.
On your Challengers, with the multipart deck structure and rather light side decks, what's moving, and how much more is it moving than when they were new, stiff boats? Certainly the NE 38 is, and the M 27 was, becoming more flexible with age.
And, what should we be doing about it?
Our North East 38 flexes enough to pop the saloon table support (looks alot like your centerboard cable cover) out of its socket (over 1/2") but she does not spit her wedges. Our Morgan 27 flexed enough, before I tied the deck-mounted chainplates down to the hull, to lift the deck 3/4" or so and spit the wedges. Dad had made special wood wedges with ell-ed tops (so they would not drop out), I replaced them in neoprene. Either way, they had to be restrained in place with an oversized hoseclamp, ugly but effective. This flexure is due to the compression load in the mast, when the rig is loaded, pushing the keel down with respect to the sides of the hull; and the deck either buckles inward or up. I can hear all sorts of movement in the NE 38's cabinetwork when this happens, and watch the table support post move in its socket; I could watch the Morgan's deck lift off the bulkheads. Additionally, the Morgan's forward keel bolt would leak when her rig was loaded.
On your Challengers, with the multipart deck structure and rather light side decks, what's moving, and how much more is it moving than when they were new, stiff boats? Certainly the NE 38 is, and the M 27 was, becoming more flexible with age.
And, what should we be doing about it?
I must stress that whilst my boat does of course move a little in places (which boat doesn’t?) – none of them worrying – there is certainly no sign of untoward movement in the mast-thru-deck area. The Neoprene wedges were originally popping out because they were just v'd wedges, without a rebate to hook over the collar. I believe that these early Alden GRP boats were well specified and built very strongly in this area. On my Caravelle I can always open and close the WC doors with ease when very hard pressed: that was one of the first things I checked during my pre-purchase test sail. See the attached accommodations plan, showing the very neat arrangement of WC doors around the mast devised by the Alden office, which takes up less saloon space than the traditional side facing door, whilst hiding the mast and presumably offering a lot of stiffness at a crucial position. It also makes the forward cabin semi “en suite” - as long as one remembers to lock the other heads door when in!
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I vote for the tried and true, wooden wedges, all around.
Call me a traditionalist but it seems to work (and I'm lazy). Initially, I lost some wedges but since have "firmed" them up a bit upon stepping the mast. Like Iain, I simply have a rubber boot (inner tube cut to size) that's taped around the mast and the collar on the cabintop. Sorry to Rod Stephens, but I can't see any reason not to secure the mast around it's perimeter in the collar. At any rate, without wedges it would simply move from side to side, fore and aft as the main loaded up.
I'm always looking for movement in my old boat. All boats have some but the area around the mast seems well overbuilt. Even though the bulkheads encase the mast fore and aft, they're not continuous so could concievably flex. If you envision a cross section through this area of hull, deck, cabin sides, doubled cabin top, athwartship beams connecting bulkheads, I believe all the rig would be ripped off the boat leaving just the stump of a mast without things moving too much below.
Frankly, I think the weakest area of my boat overall is around the companionway. This area relies on the joinery and structure of the cabin back (floating) attached to the bridgedeck (floating for some distance), the side decks and finally the coamings. Over they years I've had a settling in this area. It showed up in a seperating of the cabinback at a glue joint. Repaired years ago with a dutchemen filler, I had to add a feather a few years back. Since I have refastened much of this area.
Call me a traditionalist but it seems to work (and I'm lazy). Initially, I lost some wedges but since have "firmed" them up a bit upon stepping the mast. Like Iain, I simply have a rubber boot (inner tube cut to size) that's taped around the mast and the collar on the cabintop. Sorry to Rod Stephens, but I can't see any reason not to secure the mast around it's perimeter in the collar. At any rate, without wedges it would simply move from side to side, fore and aft as the main loaded up.
I'm always looking for movement in my old boat. All boats have some but the area around the mast seems well overbuilt. Even though the bulkheads encase the mast fore and aft, they're not continuous so could concievably flex. If you envision a cross section through this area of hull, deck, cabin sides, doubled cabin top, athwartship beams connecting bulkheads, I believe all the rig would be ripped off the boat leaving just the stump of a mast without things moving too much below.
Frankly, I think the weakest area of my boat overall is around the companionway. This area relies on the joinery and structure of the cabin back (floating) attached to the bridgedeck (floating for some distance), the side decks and finally the coamings. Over they years I've had a settling in this area. It showed up in a seperating of the cabinback at a glue joint. Repaired years ago with a dutchemen filler, I had to add a feather a few years back. Since I have refastened much of this area.
