Robbin I have a 23 and the compression post is original. Just wondering what happened to make you turn into a nautical engineer? Lol. Lenny Smith On Apr 19, 2014, at 11:19 AM, Thomas Buzzi <thomaspbuzzi@gmail.com> wrote:
Robbin, I had a civil engineer run some numbers for me on just that issue. What IS the compression load likely on, in my case with an M17, a sailboat with about 200 sq feet of sail up in, say, 25 knots of wind. It came out to about 1000 pounds. I also found out that a 4x4, yellow pine, #1 grade post, eight feet long with no side bracing will handle the compression load of about 6000 pounds. So a shorter post and one with side bracing such as a bulkhead will handle considerably more. Then too if you choose oak, the numbers would go even higher. Fair winds, Tom B
On Sat, Apr 19, 2014 at 10:54 AM, Robbin Roddewig < robbin.roddewig@verizon.net> wrote:
Hi M-list, I am trying to figure out a design for a compression post for my M-23. I have a stainless steel plate being fabricated by emachineshop that will transfer the load from the tabernacle and solid core deck to the three boards that are on the end of my bulkhead in the M-23. I am going to open the floor liner and set the boards on solid hull/keel with a glassed in block of oak at the base. I have some questions. 1.) What is the load from the mast that I need to make sure the compression post will carry? 2.) How to calculate the tensile strength (compression load) limit of the three boards (they will be epoxied together and form a U shape). I am assuming cross sectional area. And I will put in the factor for laminated boards.
Any help would be appreciated!
Thanks Robbin
All, Next week I'm putting my M15 on jack stands for a few days to touch up the bottom paint. Does the bottom of the keel need to be supported on a block while on the jack stands? The marina that is helping me caters to power boats, not sailors so they will not likely be much help. Thanks, Kevin
Kevin, I put jack stands under my boat to balance it more from side to side and blocked the keel fore and aft as well as under the nose of the keel to take the actual load. Didn't like the idea of a jack pad pressing against a thin hull anywhere. Tom B On Sun, Apr 20, 2014 at 9:05 AM, Kearns, Kevin P <kkearns@pitt.edu> wrote:
All,
Next week I'm putting my M15 on jack stands for a few days to touch up the bottom paint. Does the bottom of the keel need to be supported on a block while on the jack stands? The marina that is helping me caters to power boats, not sailors so they will not likely be much help.
Thanks, Kevin
Thanks, Tom. Very helpful. Kevin ________________________________________ From: montgomery_boats-bounces@mailman.xmission.com [montgomery_boats-bounces@mailman.xmission.com] On Behalf Of Thomas Buzzi [thomaspbuzzi@gmail.com] Sent: Sunday, April 20, 2014 11:34 AM To: For and about Montgomery Sailboats Subject: Re: M_Boats: Jack stands Kevin, I put jack stands under my boat to balance it more from side to side and blocked the keel fore and aft as well as under the nose of the keel to take the actual load. Didn't like the idea of a jack pad pressing against a thin hull anywhere. Tom B On Sun, Apr 20, 2014 at 9:05 AM, Kearns, Kevin P <kkearns@pitt.edu> wrote:
All,
Next week I'm putting my M15 on jack stands for a few days to touch up the bottom paint. Does the bottom of the keel need to be supported on a block while on the jack stands? The marina that is helping me caters to power boats, not sailors so they will not likely be much help.
Thanks, Kevin
Yes, this is essential. Virtually all the weight should be borne by the blocks under the keel. The jackstands are only to keep the boat from tipping to one side or the other. With a relatively thin-hulled boat like a Montgomery, putting too much weight on the jackstands is likely to cause gelcoat cracks. -----Original Message----- From: Kearns, Kevin P Sent: Sunday, April 20, 2014 10:05 AM To: For and about Montgomery Sailboats Subject: M_Boats: Jack stands All, Next week I'm putting my M15 on jack stands for a few days to touch up the bottom paint. Does the bottom of the keel need to be supported on a block while on the jack stands? The marina that is helping me caters to power boats, not sailors so they will not likely be much help. Thanks, Kevin
Thank you. This makes perfect sense. Glad it occurred to me to ask because, as I said, I don't think this marina has any experience with sailboats. Kevin ________________________________________ From: montgomery_boats-bounces@mailman.xmission.com [montgomery_boats-bounces@mailman.xmission.com] On Behalf Of Stanley Wheatley [swwheatley@comcast.net] Sent: Sunday, April 20, 2014 6:30 PM To: For and about Montgomery Sailboats Subject: Re: M_Boats: Jack stands Yes, this is essential. Virtually all the weight should be borne by the blocks under the keel. The jackstands are only to keep the boat from tipping to one side or the other. With a relatively thin-hulled boat like a Montgomery, putting too much weight on the jackstands is likely to cause gelcoat cracks. -----Original Message----- From: Kearns, Kevin P Sent: Sunday, April 20, 2014 10:05 AM To: For and about Montgomery Sailboats Subject: M_Boats: Jack stands All, Next week I'm putting my M15 on jack stands for a few days to touch up the bottom paint. Does the bottom of the keel need to be supported on a block while on the jack stands? The marina that is helping me caters to power boats, not sailors so they will not likely be much help. Thanks, Kevin
Yes. the keel of the boat is to take the main weight of the boat with the stands helping to balance the boat but they are not meant to take the primary weight of the boat. I have worked quite a bit with boat yard lift operators blocking boats and this is the approach always taken. You can verify this with your marina. Robbin On 4/20/2014 10:05 AM, Kearns, Kevin P wrote:
All,
Next week I'm putting my M15 on jack stands for a few days to touch up the bottom paint. Does the bottom of the keel need to be supported on a block while on the jack stands? The marina that is helping me caters to power boats, not sailors so they will not likely be much help.
Thanks, Kevin
participants (5)
-
Kearns, Kevin P -
Leonard -
Robbin Roddewig -
Stanley Wheatley -
Thomas Buzzi