I got the new stainless centerboard today but it is 11 lbs too light. Do you know a way a simple way to find the exact center of weight for easy lifting it in to place and the exact center of effort, I know the center constantly changes while under way but for records I would like to know where it is and how it changes with different sail plans. ( reefing )
If the board is not faired (flat plate) and you have an AutoCAD dwg of it (aclt works) you can find the cg easily by making a region of the outline and then check the region/mass properties. If you have a paper dwg of it you can cut out the shape and hang it from a stick pin in two places (one at a time) and the intersection of vertical lines drawn from each pin will be at the cg. If it has been faired or you don't have either of the above, you can balance it on a straight edge two times and where the balancing lines cross is the cg.... Tod -----Original Message----- From: montgomery_boats-bounces@mailman.xmission.com [mailto:montgomery_boats-bounces@mailman.xmission.com] On Behalf Of MC Carpenter Sent: Tuesday, December 02, 2003 8:08 PM To: For and about Montgomery Sailboats; Mark Escovedo Subject: M_Boats: Re: previous board diagram I got the new stainless centerboard today but it is 11 lbs too light. Do you know a way a simple way to find the exact center of weight for easy lifting it in to place and the exact center of effort, I know the center constantly changes while under way but for records I would like to know where it is and how it changes with different sail plans. ( reefing )
thanks for the tip perhaps you can give me a simple solution for this next project. I have found several different sources of closed cell foam, some pour in and some cut to measure blocks and boards, that I plan to use to achieve positive flotation, Some foam is labeled 1.7 and some 2.2 lbs per cu ft. The heavier types of closed cell I do not plan on using. Compared to a cubic ft of air, what is the best way to find the positive floatation mark on the boat to keep the height of the cockpit seat level with the outside water level but no deeper. For example: suppose the worst case scenario and the boat is completely filled with water (saltwater that is) I want the water to drain out to the level to or less than the cock pit seats.
I don't know of an *easy*, i.e. quick and dirty, way to do that. First off, short of "trial and error" (hehehe) I'd think you'd want the lines for the hull. Second, you'd have to know the weights and centers for the boat including the volume of water that can actually fill the boat (permeability....you would need to account for the volume consumed by stores, etc). Not only would you have to determine that the boat would float at that level, I presume you'd be interested in knowing that it would float *upright* in that condition. The actual calculations for a static situation aren't that difficult, but it is a lot of work and chances are would be of marginal usefulness because any situation that would have gotten you into that mess is unlikely to be very static. Do you know that the intact boat stands a chance of righting after rolling in a broach? I know a guy who sailed a Cape Dory 26 to Bermuda (and back) from the Norfolk area and when he got back he sold it and bought a BCC instead. Got knocked around too much in the CD. Sorry, no help from me on that one.... -----Original Message----- From: MC Carpenter [mailto:southisland2@earthlink.net] Sent: Tuesday, December 02, 2003 10:53 PM To: For and about Montgomery Sailboats; htmills@bright.net Subject: Re: M_Boats: Re: previous board diagram thanks for the tip perhaps you can give me a simple solution for this next project. I have found several different sources of closed cell foam, some pour in and some cut to measure blocks and boards, that I plan to use to achieve positive flotation, Some foam is labeled 1.7 and some 2.2 lbs per cu ft. The heavier types of closed cell I do not plan on using. Compared to a cubic ft of air, what is the best way to find the positive floatation mark on the boat to keep the height of the cockpit seat level with the outside water level but no deeper. For example: suppose the worst case scenario and the boat is completely filled with water (saltwater that is) I want the water to drain out to the level to or less than the cock pit seats.
I have installed 27 cubic feet of styrofoam beneath the decks of Carpe Ventum (M-17#604), and I have also installed a Whale Gusher 10 bilge pump, with the pick-up in the bottom of the bilge. It's located in the cockpit about a foot forward of the aft cockpit locker. The pump handle is on a tether and kept in the aft locker, as the pump would be useless without the handle. The product of combustion of some of the pour-in foams can be deadly. Something to consider. Also, with the in-place-foam, access to that area for future maintenance could be difficult, if not impossible. ----- Original Message ----- From: MC Carpenter To: For and about Montgomery Sailboats ; htmills@bright.net Sent: Tuesday, December 02, 2003 10:52 PM Subject: Re: M_Boats: Re: previous board diagram thanks for the tip perhaps you can give me a simple solution for this next project. I have found several different sources of closed cell foam, some pour in and some cut to measure blocks and boards, that I plan to use to achieve positive flotation, Some foam is labeled 1.7 and some 2.2 lbs per cu ft. The heavier types of closed cell I do not plan on using. Compared to a cubic ft of air, what is the best way to find the positive floatation mark on the boat to keep the height of the cockpit seat level with the outside water level but no deeper. For example: suppose the worst case scenario and the boat is completely filled with water (saltwater that is) I want the water to drain out to the level to or less than the cock pit seats. ------------------------------------------------------------------------------ _______________________________________________ http://mailman.xmission.com/cgi-bin/mailman/listinfo/montgomery_boats
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