I don't see any problems with positioning the reinforcing webs wherever convenient. They might be angled aft, so that they are still orthogonal to the partners tube, for instance. The main thing is that they act to stiffen the partners-to-deck join and the deck-to-hull join.
Thanks David and Graham, that helps. Graham, I think I should be able to implement webs of the scale you have, but put them below decks, so it is nice to know what you have is working.
David, I like your implementation of the arch that extends all the way to the topside stringer and I will extend the triangular webs for Leeway such that they continue to the topside stringer.
David it looks like your reinforcing arch is aft of the mast partners. This makes me wonder if I might simplify things for myself by attaching my triangular transverse webs to the aft 1/4 of the tube that forms the partners. If you look at the location where the tube goes through the deck, the existing 2" angle deck-stiffener passes slightly ahead of the mid-point of the tube.
Thus, I either have to remove this stiffener to make room to weld the triangular webs, or I could attach the transverse webs slightly further aft on the mast-partners-tube and leave the existing deck stiffener in place and welded to the side of the tube. My first instinct was that the transverse webs should be located on the midpoint of the sides of the tube, but if they could be moved further aft that would simplify the installation and allow the additional stiffening of the existing framing to be left in place as well as adding the triangular transverse frames (see Option B below).
Any thoughts appreciated.
On Arion, another steel boat, I welded a steel tube, with braces to the hull, for a step, then cut a hole in the cabin top into which I inserted and welded another a steel tube. Because my cabin is so small and I wanted to minimize intrusion, I added the bracing structure to the outside, as you can see in the attached photo. I had to cut through a fore and aft stringer in the cabin top, but welded this to the tube once it was fitted. I also put small knees fore and aft of the partner tube on deck, then added an athwartships brace that went right out to the gunwale. The part of this athwartships brace on the cabin top gave me attachment points for halyards, lifts etc, and the part on the side decks formed a cutwater that keeps mud from the anchor chain on the foredeck, so it has more than one purpose. I felt the need to brace it securely but may have overbuilt it, as is my tendency. After 5000 miles of often vigorous ocean sailing, it is well-tested. I do feel a shudder in the cabin top occasionally when the boat is pitching hard, but there has been no signs of serious movement.
Click on the image to see full-size.
The situation is remarkably similar to that on Weaverbird, where I had to cut through a deck beam as well. I decided to add a deep plywood arch, bonded to the remains of this deck beam, extending down as far as the topside stringer, as an excess of rigidity in this area can't hurt. I think you might do something similar, and extend the triangular web athwart the mast partners to make it a quadrilateral that meets the stringer.
This has been a big week in Leeway's refit. After far too long taking care of other parts of the refit, I'm finally working on the Junk Rig (which was a big motivation for the refit). I've re-read PJR and searched the forum, but there isn't much information about mast partners in a metal (aluminum) boat. I have the mast step fit in place but I'm a bit stuck on the mast partners and would welcome any thoughts on my proposed mast partners.
As a bit of background, Leeway came with freestanding masts as part of a staysail schooner rig. Fortunately the main mast is in a workable location. The main-mast-partners consists of a 11 3/4" (298mm) ID, 3/8" (10mm) wall tube to accept a 10" (254mm) OD aluminum mast. The deck plating is 3/16" (5mm) thick and has a 3/8" (10mm) thick doubler around the tube as part of the mast partners. This mast benefits from its location on the back of the coachroof which acts like a deep transverse frame.
Below deck the tube that forms the mast partners is supported by triangular webs made from 1/4" (6mm) plate.
Unfortunately, I have to move the foremast to fit a junk rig. The best location for the foremast is in the middle of the fore-deck and thus there aren't very heavy transverse frame members present. The 3/16" (5mm) deck plate in this area has 2" (51 mm) angle transverse frames as the stiffeners. Shown is red is the cutout where the tube would go for the mast partners. It will cut through one of the 2" square transverse frames.
Zooming out a bit, the hole for the mast partners would end up 12" (305mm) aft of the small bulkhead and 24" (610mm) foreward of the 6" (152mm) tall ring frame show in the foreground of the photo below. My plan was to add triangular webs like those on the foremast to support the tube below deck.
My original plan was to reinforce the fore-deck with two 1/4" (6mm) thick doublers. The foredeck has a fair bit of camber, so the plan is to use two stacked doubler plates that can more easily be bent to follow the deck, rather than one thicker one. One plate (shown in green) would be 30" diameter, with another 22" diameter (shown in blue) laid on top of that. There are also some holes leftover from the windlass that will need to be dealt with.
My question is, does this sound reasonable, or is more substantial framing required below decks?
I posted the result of my test of the Dewalt drill as an electric winch handle in a new thread here.
If only I had a cockpit! Seriously though, I don't think there is space for boxes. If you look at this drawing and this picture, you can see that things are a bit cramped as they are. Also, making PJR-style storage reels shouldn't be too arduous (I know, famous last words). The plan is to make the reels using PVC pipe and PVC sheet. To mount them, I just need to weld aluminum spindles to the hull.
just a quick one before hitting the bunk:
A power capstan needs not be destructive. Just pass the rope a single turn around it before starting up. Then you will need to haul a little on the rope and if anything jams, the rope will just slip on the drum. That is how it works for me, at least.
PS. Most of the ball bearing blocks I use (alle the single blocks) are so-called heavy duty, with steel balls and race.
I've drawn my line reels base on 10 mm line and a 3:1 purchase. If 3:1 turned out not to be enough, then I suppose I could go for a high-strength line of smaller size and still fit it on the same reel.
Thanks Arne, that's interesting, as usual.
You are right that Dewalt drill only has about 1/4 the torque of the winchrite. This is largely a result of being a 12V tool. The manufacturer for the winch bit lists the sister model to this drill as one of his preferred tools when really high torque isn't necessary. I found one for sale second hand in my neighbourhood and figured it was worth a try. The lower torque does have the one advantage of making it more difficult to really mess things up. One of things I don't like about powered winches is that you have incredible power at the push of the button. Thus, it only takes a moment of inattention to jam or break something thoroughly. We'll see, right now it is a cheap experiment. I'm still consider the Pontos 4-speed winch whose lowest gear has a power ratio of 112.9:1, so with that winch the lower torque of the Dewalt drill could be made up by the winch gearing, albeit with a slower haul rate.
Given my high AR sails, a 5:1 halyard would be a fair bit of line to store. I am interested to see what numbers you come up with for mast compression from the halyard. I've drawn my line reels base on 10 mm line and a 3:1 purchase. If 3:1 turned out not to be enough, then I suppose I could go for a high-strength line of smaller size and still fit it on the same reel.
I was planning on using the Garhauer ball bearing blocks that I think David and Annie have had success with. I'm not sure how these would compare to the Selden ones, but halyard blocks do seem like a spot where life can be improved by spending a bit of money.
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