So I’m finally getting around to posting some information on the Ghost Train I have started. I decided to build it pretty much stock first, then modify/rebuild floats as needed in the future.
I started by drawing the frame templates in autoCAD set up for 3/4 inch extra space at the bottom to use as a clamp. Also, is a locating arm sticking out the bottom of the template to align the templates. Of course, the left and right templates are symetrical.
I’ll attach a sample of the PDF of the float and main templates. The other two are too big and I wil gladly Email to anybody.
Here’s a pic of the jig to cut the foam at a right angle exactly 4.8 inches long. BTW, I “found” some styrofoam at work and it is very light, around 1#/ft3.
Here’s a pic of the float hull glued together with Gorilla Glue. I glued the right side pieces and left side pieces togther on a flat jig to keep it straight. Hot wire cut 1.3 inch dia. holes at a 45 degree angle in one half for the 3/4" PVC connectors coupling that will be used for the arm connections. I decided not to hollow out the floats. Then glued them all together.
I put a short piece of 3/4" PVC pipe in each coupling just on the inside side of the connector. This will allow the arm to insert into the round connector and bottom out on the shoulder inside the coupling. I will need to machine 4 round pins with shoulders to go in the sockets. Just need to figure out how to transition from the pins to the arms…
I still have to fair the hulls but the styrofoam sands beautifully. Also I need to insert the hard points for the backstay. Should the backstay be attached at float CL or near the float socket?
As for backstay, you could consider using forestay and a side shroud only. On my 1 Meter, I used a bridle wire from each crossbeam tube end, with the wire from the front beam a bit longer than the one from the rear beam, which angled the side shroud aft. The side shroud merely hooks into loops at the end of each wire bridle and makes an upside down “Y” - with one leg slightly longer and the other slightly shorter. I am allowing the mast to self-rotate, so adding a rear stay would prohibit any mast rotation.
If you are going with a swing-rig that uses a rear, backstay, I would run the backstay to the middle of the main hull and behind the rear beam for attachment. Be sure to leave clearance for the leech of the mainsail to clear the backstay during a gybe.
The other reason to use a backstay is if your mast is soft and bends easy. It might be necessary to control mastbend that way, but most multihulls seldom use a backstay.
Just a thought.
For my boat, I am using a vertical 1/8" thick ply spine for cross beam. I am cutting a slot into the end of the beam and am gluing in a piece of carbon arrow shaft. This will insert into a socket in the floats. The rig will help pull the float toward the cross beam and will keep it all together. I may need to add a second SS socket head machine bolt to assist if I find too much flex and slop with the slide-in tube/socket arrangement.
Until there is a viable class racing here - the ability to knock-down for transport is critical so some flex will be given up to achieve a quicker assembly. I think we have two other boats ready to build this winter, so once we start sailing against each other, I can’t tell how much flex is allowable between beam and float - if any.
Keep on with the build. Your posted photos will help others visualize the building process - and may encourage more to the class. A great way to start out the new year.
Thanks for posting pictures of your build. That’s a really clever idea with the jig! Probably makes short work out of cutting each section. If you don’t mind, please continue posting progress on this project. I’m betting alot of people are following it. Are you simply butting the tabs that you left at the bottom of the templates to the bottom edge stop of the jig to get the alignment correct? Also, is that hardboard you are using for the template? How does that work out with the hot wire?
Regards,
Mark
Oops! Just re-read your first post and you clearly stated that you use the tabs at the bottom of the template to align the templates…Sorry, please excuse me!
Yes, the tabs butt up against the jig. The hard board is just OK with the hot wire. The hard board needs to be sanded smooth so the wire does not hang up. I was given the recommendation to add some thin wire to the templates circumfrence so the hot wire would slide along the wire on the template, but I decided I didn’t need it.
I have completed a little work on the GT this week. I have routed out a 3" long x 1/2" x 1/2" deep groove in the floats for the stays hard points and will glue in the hard wood tonight.
I have also started hot wiring out the insides of the main hull.
two items that came up when I was trying to explain your method to folks here at work…
Do you have the forward section templates you are willing to share as you did the rear templates (above) ? There are only five sections from stern to mid-ships. There are another 5 for mid-ships to bow. Are those available to be shared?
A reminder in order to get the other side of the hull or float (when split vertically) you have to reverse the templates from one side to the other in order to get a mirror image - other wise you end up with two of the same sides of the hull/float. Since most monohulls are built entire bottom hull facing up, they don’t have this problem and simply add the deck later. This plan calls for building deck, side, and bottom of each half all at the same time - so the templates must first be cut in order for the starboard side, and then in reversed order and cut for the port side.
Hard to explain - just need to remember you need “Mirror” sections, not duplicates of same.
You are correct Dick about cutting the mirror images of each part, the templates need to be swapped end for end in the jig to make the other side piece. Now for the floats, you need to make two of each so it goes pretty fast. It took about 4 hours to cut the foam into 4.8" chunks and for two floats ond one hull. 60 pieces total.
I am glad to share the pdfs. They were just too big to post on the forum site. Anybody who wants the pdfs, just PM me and I’ll pass the files along. I also have the dwg autocad files for those that have the ability to open those files.
Now that I have started the fairing of the hulls, I have noticed the glue joints are not fairing as well as the foam. Becuase of this, I would recommend future builds not to glue to the edge, but stop the glue about 1/4" from the edge of the hull. The strength will not be in the foam but the combination of foam and fiberglass.
I tried using hot glue on one project and also found same to be true - stay well inside the exterior of the hull - besides, you’ll be covering with epoxy/glass so everything will be held together even if glue gets wet from inside.
So I have started hollowing out the main hull with the hot wire. I’ll attach the plan on what I expect to hollow out. The sail winch and rudder servo will sit directly on FG reinforced styrofoam. One problem I have encountered is the GT plan calls for the turning block to be placed at station 0, but I will leave the foam between 0 and 1 solid as it is very thin. My concern is the sheet will only have 4 stations to run or about 19.2 inches. I need to do some math to see if this new sheet movement will allow the main and jib to go out completely. If not, then I will have to move the sail servo, pot and rudder servo back one station. Also, I don’t want to use a pull/pull for the rudder, so I will probably mount the rudder servo aft of the pot and just use a CF rod.
I have added some 1/2" sq hard points to the floats for the stays connections at the design location of CL of the float 895mm back from bow. The wood is 3" long so it shouldn’t pull out.
The other photo is the main hull showing the foam removal from the forward 4 sections. I decided to try to leave in the center section to assist in transfering the vertical loads of the jib stay. The hot wire didn’t cut on the template as well on these so I have some sanding to get them to the correct size.
I finally got a few hours to work on the Ghost Train today. I fabricated the stand to help align the hulls in preperation of fabricating the arms. I also completed hollowing out the main hull from frame 6 to 10. I decided to remove the vertical foam that I previously left in frames 3 to 6. I am concerned the middle vertical foam will foul the sheeting system runnning to the bow. I also hollowed out some of the area in the foam from frame 0 to 1 to make room for the turning block. I did leave the vertical foam in the sections that contain the mast step and keel. I want the foam there to help when I route out the keel and mast step and help support the mast and keel structure.
I’ll attach some photos showing the stand, the fwd left and right sections of the main hull and the aft sections glue drying in my special “Kitchen Jig”
I’m starting to plan out the main hull internals and now I have a question concerning the main sheet and jib sheet leads. The plans call for the jib sheet to exit the deck and go through a turning block on the jib boom and back down to a deck pad eye. This effectively allows the jib boom to move 1/2 as much as the sheet movement. Now the main sheet is exiting around the base of the mast and goes to a turning block on the boom and the sheet is led to the top of the aft arm at CL. Doesn’t that also effectively move the main boom 1/2 as much as the sheet movement also like the jib boom? This wouldn’t be a problem but the jib boom is much shorter than the main boom.
Any body have thoughts on this?
Will post some more pics tonight on the main hull and templates for the arms I am working on.
Download the US 1 Meter Construction Hints and Tips.
They do an excellent job of laying out a variety of winch arrangements and one may fit your needs. It also provides info on calculating how much sheeting lengths are needed.
On my 1 Meter, I elected to go with a 2:1 and double arm above the deck. Doesn’t look as “pretty” as under-decks but easy to adjust or repair.
I’m probably going to come up from under deck near stern, and have my main line run above deck, to which I will attach two leads - one for jib and one for main. This is similaar to how Seawinds run their sheeting and seems to work. Again, puts all the lines above deck for easy access.
I completed glueing the hull halve pieces together. Notice in the picture the flat foam sections that I have left in the hull to use as the mount structure for the sail winch. BTW, I have a spare RMG ready to install, but I was wondering if I could get away with a less expensive winch?
I have also started fabrication of the arms using 1/16 lite ply as the center spline. The arm center spline is made in sections. I fabricated lite ply to fit in the 3/4" PVC coupling. 1.080" OD which then goes down to .930". In order to ensure correct hull alignment, I set the arms in place, then glued the coupling connectors to the arms with the hulls in place in the jig. Next for the arms is to start building the arm center splines up with some 1/32" lte ply and foam.
Finally getting back to building my trimaran. Family issues and IOM regattas got in the way.
I completed roughing out the arms tonight. The were built up using 1/2" sheet styrofoam and glued with gorrilla glue. I hand carved the “pins” to connect with the 3/4" pipe connectors. They will be finished up when covered in fiberglass.