I’m mostly done with my Kittiwake II (K2) hull, and I’m starting on the rig.
What I would like to discuss is the possibility of making the mast into a two-piece unit so it would be more transportable.
According to the build instructions, two-piece aluminium the mast is permanently glued at the joint to make the height 22"/560mm, but would it be possible to use a pin instead so it can be disassembled? I think I would glue in a solid plug into the inner tube, and drill through both tubes, with some sort of removeable pin to assemble the mast to full height for sailing.
Since the mast could break down to about 12 inches ( a foot) I don’t think it would be worth the trouble to remove the boom, and the sails could be easily rolled for storage, and all should fit into a container suitable for transport or shipping.
Why not just puch yout plug down the larger tube to the point where it gives the smaller tube sufficient bury and glue it in at that point. The only forces you are possibly trying to resist are in compression, so why the pin?
Your idea would work, since only compression(via main sail luff) would be needed to keep the mast together. Remember that originally, the two mast tubes are glued together. The pin would be used to ensure the mast will not come apart (opposing Murphy’s Law.) Plugging both tubes and a small screw in one plug, so the two lengths could be screwed together, could also be used instead of a pin. I’m now inclined to use one of these two new methods, instead of a pin through the side, which would create a point of weakness.
You might want to pin the mast to keep the top part from rotating. I built an original Kittiwake, and found the mast would rotate at times causing the gooseneck to be off to one side. I found a tiny screw in a junk tiny toy RC car and used that to pin the mast. I was able to use the screw to tap the threads into the mast after drilling a hole in the mast slightly smaller than the thread diameter. It has worked well so far.
I know any additional hole is a stress riser, but the aluminum mast is plenty strong, and the compression force could be supported by the suggested plug. The screw would just prevent rotation.
Since I started building footys I have been keeping a look out for tiny screws (or any other useful hardware). I do not have a source to purchase anything like that around here. Old junk 35mm point and shoot cameras can be a good source of tiny screws.
The top section of the mast should not be rotating. The sail is attached using loose loops of string which shouldn’t be enough to turn the tube. As for the bottom section, if it is turning, then your gooseneck must not be moving freely enough. You’d need to key the foot of the mast into the step or the hull to keep the bottom rotating.
On a Kittiwake the forestay, jib, and head of the mainsail are attached to the masthead in a way that could possibly cause the mast to rotate on a windy day.
The gooseneck was two split pins locked together. Sometimes in a jibe they could lock together and cause the mast to rotate. It was much easier to add a small screw to lock the mast than it would have been to key the foot of the mast into the mast step or hull. I believe I got the idea to pin the mast from Graham at the Sheboygan footy regatta.
Hi Greg, the K2 boom design with one split pin set into the end such that the boom end acts as a shoulder on that split pin has stopped the locking pin thing from happening so far. Just one of the detail improvements over the original Kittiwake. For anyone who has experienced the locking cotter pin syndrome the fix is to use rigging thread. Loop two or three turns of thread around the mast and through the eye of the cotter pin attached to the mast. Set this up with a little thin cyano to harden and seal the thread… cured. In fact I think it was Greg (above) who showed me that so due credit to him. I have used the method since and it worked for me on Holly the gaff rigger.
Hi Tomo, I didn’t know you had one Looking forward to reading how you get along.
I think I might try something new with the boom-end cotter pin:
I would either make a U-shaped thing of a cotter pin or a length of wire, and attach it to the main boom end by wrapping it with string (no carbon tows) and coating with resin.
On power boats, the rudder pushrod is a two-piece deal connected with a wheel collar. In the powerboat, it allows you to remove the entire radio box as a unit. On a sailboat, it allows gross adjustment of the ruddder pushrod. I use a wheel collar as small at the pushrod with an elongated hole, and grind down as much as possible. (see below)
I’m finished building the hull, except for waiting for the epoxy to cure, which should be only another two or three weeks. I used Gorilla glue for almost everything, but some parts that I wanted to setup up quickly (Gorilla Glue takes about 6 hours to set up, 12 to cure.)
I did use some CA on the deck-side seam to get the deck seam to be tight. The hull will look nice after finishing.
the only other deviation I did to the excelently-written assembly instructions was to use the Bluebird MS-280MG micro servo for sail control. Since the supplied servo tray has a hole for a standard servo for the sail control, I had to fill the hole with a piece of ply and cut a hole for the Bluebird servo.
Next on my build is to seal the hull with Polycrylic gloss clear, and some kind of color. Then possibly some more Polycrylic, and some decals; maybe some ricer-style stuff from an r/c car. I’m still working on the zip-lok idea for the deck patch.
I sealed the birch plywood deck of my Footy with at least three coats if Minwax polycrilic (actually, I think it may even have been four), and while it looked great, after a day’s sailing in very strong winds, I noticed several dark spots had developed, particularly near the edges along the sheer, and also along the hatch opening. After a few days of sitting in the air-conditioned house, the dark spots disappeared, indicating to me that they were caused by moisture seeping into the wood through the polycrilic. I then put on two coats of Minwax’s solvent based clear polyurethane varnish, lightly sanded between coats, and I haven’t seen the dark spots since. I suspect that since it is originally water-based, the polycrilic isn’t totally waterproof when dried, and will allow some moisture to soak into the wood. The oil based polyurethane seems to seal better against moisture than the polycrilic. I would still use a couple of coats of polycrilic on a Kittiwake (or any other hull with foam parts) first, followed by a couple coats of solvent based polyurethane, to protect the foam core from the solvent contained in the final coats of the polyurethane. For a colored finish, I would think that a coat of enamel spray paint should effectively seal the polycrilic, but I would try it on a sample first, to be sure the two are compatible. I’ve had pretty good luck with Rustoleum’s gloss white spray enamel, though it does take a bit longer to dry than some other brands. I’ve also had good luck with Krylon’s spray paints (not water-based), but haven’t tried their “Fusion” yet.
I have had similar experience with polycrylic on other boats Bill, I just don’t think it is up to the job. My number 1 varnish is Minwax Helmsman in the can. It can safely be painted directly onto the EPS foam I use so it’s easy to seal the inside of the hull skin in the radio bay. It must be thr brushing varnish though because although the spray version has the same name the propellant or solvent in the spray will dissolve the foam.
When I paint a ply or balsa hull I have settled on two coats of thinned Z-Poxy laminating epoxy thinned with about 25% isopropyl alchohol (anticeptic). Over that I spray Krylon or XO-rust. The enamel paints need a month to cure though, yes they are dry after a half hour but stay soft for a long time. I have a stockpile of the old formula (lacquer) Krylon for speed. I intend to try Krylon Fusion as I look to the future when my store is depleted.
I did a little reading over at www.Minwax.com , about Polycrylic and the water-based polyurethane, and it didn’t say if any of the products were waterproof or dried hard when cured. I use Polycrylic on furniture like desktops and nightstands and it holds up just fine.
I must’ve gotten an odd bottle of epoxy, or you need to stir it up before use. The syringe ones all work fine but are more expensive, so I use the Gorilla Glue.
I finally found something to coat the hull at the HomeDepot store. It’s called “Parks Water Base Polyurethane” and it comes in a 1 gallon plastic jug. It’s a heavy-use floor finish (like for gymnasium floors) and dries to a very smooth, hard, waterproof, glossyfinish.
I applied about 10 coats because I applied it thinly, with a light sanding between coats if I saw any runs or brush marks.
It sure beats epoxy, you can use it indoors, and I’ve even used it to soak fiberglass cloth to cover some balsa Footy hulls.
I used Gorilla Glue to glue the panels to the foam, because I still have a small bottle of it. The glue foams a little and really attaches better to the foam core. You can even see a little oozing out of the seams inside & outside, which tells you the seam is well glued.
not having seen a K2 up close, but looking at the pics on scalesailing… I would think that the forestay would keep the top of the mast from rotating, you’d need to be sure the bottom section has a firm connection at the deck/hull to keep the boom from rotating the bottom portion of the mast. in stead of using a pin to hold it together what about using some of the sugrical/fuel line rubber tubing across the joint to hold it in place… rather than the pin… another option would be to add a masthead crane, a bumpkin and install a backstay. this woudl also allow for another method for tuning…
Personally I feel that keeping the rig as one piece helps prevent damage to the sails, tangles, ect…
also you’ll need to loosen the down haul on the main each and every time to allow enough play since when you slide the two peices together the mast will be longer at least for a moment until the joing slips together. if that makes sense.