 |
 | Home | Contact Us | FAQ | Search & Site Map | Link to Us |
 | Sign In | Join | Other 45 Sites in Network |
| HomeDiscussion GroupsBoatsPaddle BoatsSailingCruisingBuildingElectronics Related Topics CarsMotorcyclesMore Topics ... |
Boat Forum / Building / June 2007Building a new wooden boom
After 35 summers in a pretty rainy corner of the world (Kiel, Baltic Sea), the old boom has done its job, building a new one has started. Now, weighing the raw timber in my hand on one side and comparing it to the old boom, the question for hollowing the new one to reduce the weight arises. It will be put together from three parts, two adjacent 1.5" * 3" stripes with the rail for the keep (?) routed out, and one 3" * 1.75" in landscape-format below, overall length 11 feet. How deep and over which extent would you take out material, using a router? Thanks in advance for all helpful comments! U. Ulrich, It looks like you are trying to create a 3" diameter boom with a foot rope tunnel (I hope that is what you mean by keep). Assuming that this boom in not mid-boom sheeting, and that you are not planning to vang it very hard to flatten the main. Let me make some observations and recommendations. The nature of such a structure is such that the material in the center does very little. A spar of the size you are considering, could easily loose the center 1" of material - almost - the conditional is because I do not have the final dimensions of the keep (tunnel). If you removed material so that the remaining material was no less than 3/4" everwhere with the exception of directly under the tunnel where it could be a little less for just that tangent. The structure is best left solid about 3~4 diameters from both ends this is largely for fittings and fastening. That said, you can take a lot of wood out of that bottom piece and maybe some out of the two upper parts. I am guessing that you all ready have the material. If I were making this spar, I would not make it round. I would make it tall enough to accommodate the tunnel without reducing the loaded section very much. Over very many years, my father and I assembled many such spars some are still in use today and the last was layed up over 25 years ago. We did it much the way you seem to be headed. We would cut staves and route the tunnel and hollow the center then laminate the spar (later with epoxy) and finally plane the final shape. Best of luck Matt Colie Lifelong Waterman, Licensed Mariner and Perpetual Sailor > After 35 summers in a pretty rainy corner of the world (Kiel, Baltic > Sea), the old boom has done its job, building a new one has started. [quoted text clipped - 10 lines] > > U.  Signaturetarget of diversity victim of affirmative action refugee from the war on poverty minimized by political correctness Matt, thank you very much for that explicit and experience-based comment. Yep, keep is the german word, the foot rope is what I had in mind. A quick calculation shows, that I could reduce the wooden volume by about 10 to max. 15% of the whole mass, if I do not work down to the lowest stability level. A friend of mine, carpenter by profession, boat builder by heart, did me the favor to shape the wood down to the final surface, with the tunnel neatly done, and a slot of 1/8" for the sail. Carrying all three parts (which are still 3 feet too long) and comparing that to the old boom showed that the new one does not weigh really more than the old one, rather less, when processed to the final result. So, I guess I will leave the volume solid as it is right now. Even 15% less weight (even less, when looking at the total weight with all the s/l steal fittings) is not worth the extra effort in this case. But the discussion was it - every word. So again, thanks for your comment! Cheers, U. >Ulrich, > [quoted text clipped - 48 lines] >> >> U. Ulrich, Sounds like you have a good friend there. When you get it planed round, it will loose even more weight. Have a good time gluing it. You can't have too many clamps. I would lend you an arm load, but the shipping would be a problem. Good Luck Matt > Matt, > [quoted text clipped - 71 lines] >>> >>> U. Signaturetarget of diversity victim of affirmative action refugee from the war on poverty minimized by political correctness >Ulrich, >Sounds like you have a good friend there. >When you get it planed round, it will loose even more weight. >When you get it planed round, it will loose even more weight. Matt, since the fittings taken from the old boom are shaped to fit a more rectangular pattern, I had to reproduce that here. The boom sleeps in the living room right now (in its raw parts), it is really a sight. The tunnel is absolutely straight, you can see through it without obstructions. (The old boom, as I discovered only after the disassembly, resembled more a bow (the one to shoot arrows) - no wonder the boat sailed better on starboard bow than on port :( ) I'll varnish the tunnel sides and the slot before glueing the two top parts, and then the task will be to keep the straightness during the glueing and setting the clamps - got quite a collection here, and maybe the friend will borrow me some more. Thanks for the encouragement :) U. How much is a wooden boat allowed to leak (plank on frame) and be considered normal or healthy? Simple common question, i'm sure, but of great importance to me at the moment (you can imagine why) Stefan > How much is a wooden boat allowed to leak (plank on frame) and be > considered normal or healthy? It depends. Has the boat been in the water for a while? Then the seams should leak very little or none. If it is a sail boat, the topside planks will weep when the boat is heeled and that area is in the water. If the boat has been dry for a while it may well (probably will) leak like a sieve for 2-3 days until the planks swell. SignaturedadiOH ____________________________ dadiOH's dandies v3.06... ...a help file of info about MP3s, recording from LP/cassette and tips & tricks on this and that. Get it at http://mysite.verizon.net/xico No, unfortunately she's been in close to 3 years after a complete rebuild - long story - and that's what i needed to know. thanks! >> How much is a wooden boat allowed to leak (plank on frame) and be >> considered normal or healthy? [quoted text clipped - 6 lines] > If the boat has been dry for a while it may well (probably will) leak > like a sieve for 2-3 days until the planks swell. > How much is a wooden boat allowed to leak (plank on frame) and be > considered normal or healthy? The old Viking saying (from somewhere in the Islandic Sagas) says that if a boat has to be emptied only twice in three days, it is safe to take to the sea. I suppose that included rain water, as they were open boats... We just launched an old 8-meter boat, been on the dry all winter. At launch we quickly installed an electric pump, and it was busy. We moved her to a place with good electricity, and had to wait to see if the pump switch would go on and off as it should. The next day we sailed her a home, a few miles. And pumped her empty. The next week one of us went to check her twice a day, and occasionally pump her empty. The week after, there was no problem. Now (a month later) there is only a small pump running from the battery. When we are out sailing, and she tilts a lot (as such boats do), the pump runs 10 seconds twice an hour, emptying no more than a liter or so. More if it has been raining... -H |
Reply to this Message |
 Sign In
 Join
 My Latest Posts My Monitored Threads My Blog My Photo Gallery My Profile My Homepage Start New Thread Enable EMail Alerts Rate this Thread
|
©2009 Advenet LLC Privacy Policy - Terms of Use
This website includes both content owned or controlled by Advenet as well as content owned or controlled by third parties.