compression post and storage

[skip1930]

Rob said, " I sure do wish that some people would keep there fingers off the key board when they relay don't know what there talking about. The foam is there to keep you afloat should you ever take on water. "

I must respectfully disagree.

Rich Hutchin's talking at the All Sail Boat Show at Navy Pier in Chicago stated, " No amount of foam will keep a keeled Com-Pac afloat. Not with 600 lb of concrete in their keels." We were talking about Com-Pac 19's.

I believe in Bob Burgess's book 'Handbook of Trailer Sailing' about the same thing was said. And embellished to include foam is for stiffening and quite running when beating into the seas.

I don't know what model of Com-Pac we are talking about here. What ever it is let's tie it to a dock and fill it up till it sinks or floats.

skip.

[Bob23]

I like this discussion. I'm sure there's a scientific way to determine how much foam is needed to float your boat. But, as Mr. Miyagi so eloquently stated in "Karate Kid": "the best way to avoid a punch is to not be there".
Keep the water out of your boats and you won't need any foam! When it's rough, put the drop boards in. Keep the foam for the pfd's. In my ever so humble opinion!
bob23
Man! I would need a s--tload of foam to overcome the 1350 lb. keel in my 23! There wouldn't be any room for me!

[Pete H]

Hi Guys,

Rob23 mentioned that there must be a way to calculate the amount of foam neede to provide positive buoyancy for a boat. Yes there is, and here it is.

This formula is metric, sorry. Australia changed to the metric madness system about fourth years ago, and it took me nearly that long to get used to it, but now I'm so indoctrinated I can't mentally convert back to feet and pounds etc.

The buoyancy needed to float a boat: =  1.2x (MxK+F)/1000-D
                                                                                                where M=hull and deck mass in kilograms
                                                                                                           K=constant for hull material, Fibre glass=0.37
                                                                                                                                                      Aluminum=0.62
                                                                                                                                                       Steel=0.8
                                                                                                           F= mass of machinery, fittings, rudder,centre board and
                                                                                                                ballast etc.
                                                                                                            D= density of buoyancy material in kilograms per cubic
                                                                                                                  metre ( 35 kg. for foam approx)
For example for a Legacy, the design mass is about 500kg, but 200kg of that is ballast, so we have about 300kg of fibre glass so       
M = 300,   F = 200(ballast)+ 100kg for anchors, rudder, centre board etc. and 30kg for the outboard

Which allows us to calculate the buoyancy needed as:

1.2x(300x 0.37 + 330)/1000 - 35 = 0.55 cubic metros, say 0.6 for safety. This will float the boat but not necessarily upright, that depends on positioning.

Regards
Pete H

[skip1930]

Bob23 says, " Keep the water out of your boats and you won't need any foam! When it's rough, put the drop boards in. Keep the foam for the pfd's. In my ever so humble opinion! "

Precisely. Corks don't sink. Button her up and stay in the cockpit with a PFD on.

skip.

[Rob]

 I cant believe that a manufacturer will come out and say my boat sinks ,I haven't been in the coast guard regs lately but Iam sure theres something in there about floation that even dates back to the early Com Pacs .There is alot of good information and shared experience on this site its truly a shame that some posters dont know there limits.     Rob

[Salty19]

Rob, I think an apology is in order. The posts about floatation are correct as they relate to compacs.

Read the regulations. Sail and other certain crafts are excluded from floatation regulations.

http://www.uscgboating.org/regulations/boatbuilder_s_handbook/flotation_part1_a.aspx

Most power boats? Sure, they float.

Enough foam can be installed to keep it afloat! But what's there is for stiffening and quieting reasons from a design perspective.

[Bob23]

Pete:
  Thanks for the equation. Finally, math I can use! If I get ambitious, I may search for a non-metric equivilent but this will do!
Rob:
  Now, now...let's remember that we are all flawed human beings here. This has (and is) an interesting discussion. Frankly, I never thought about how much foam would be needed to float my boat. But it is something I'll use sometime during some future boat building. As an aside, my 1985  Compac 23/2 has no, I repeat, no foam whatsoever. Dang, there's not enough room in there to begin with...I don't plan on giving any real estate to foam.
No worries, mate!
bob23

[Bob23]

I remember reading an article by Dave Martin who, along with his wife Jaja and 3  kids, went on very long sailing adventures, somewhere close to the Arctic circle. As he was preparing his sailboat, he sealed off any cockpit lockers and made them watertight. He may have just glassed over them, don't remember. But he did shrink the size of the cockpit to very small by adding blocks of foam and glassed over them. And he enlarged the drains. His thinking made good sense: He knew he'd eventually take green water into the cockpit. The idea is to drain it before the second wave sinks the boat. He may have had watertight doors to the cabin. The article is somewhere in an old Good Old Boat magazine...lurking somewhere in my office.
I'd like to think if I had sealed cockpit lockers in my 23, that she'd float with the cockpit full of water. But I don't plan on filling it to find out.
Bob23

[Rob]

I still cant believe a manufacturer would say his boat sinks ,The Lawyers will eat that up.Thanks for the link to the regs Ill have do some research its been years since I worked in my Dads boat yard and I do remember theres alot different regs .And as I said before there is alot of good information on this site its truly a shame that some posters don't know there limits. Rob

[Bob23]

Rob:
   Let me lay it on you staight: This is not a place for personal attacks, whether direct or subtle. You've made 3 references to someone who "should keep thier fingers off the keyboard" and "don't know thier limits." Hell, that could be all of us! I suggest that if you have a problem with anyone posting here, you work it out via personal message. If someone has offended you, let them know and work it out. In the distant past, we've been down this road before and I have been as guilty as anyone else for shooting my mouth off, probably more so. Some exchanges in the past got heated and alienated some wonderful people. When I was at fault, I sent a pm or email and apologized. In the interest of keeping this a great place to hang out, I suggest you might do the same if someone has offended you.
   We are trying to keep this a place for the exchange of info, experiences as well  some good old ribbing, of which I have been the well deserved recipient many times!
  I've appreciated your posts. You are right about this being a source of " alot of good information and shared experiences". We're just trying to keep it that way. Personally, I'm wondering if I'm the "someone". I guess I'll recieve a pm soon if I am!
bob23

[Rob]

Bob 23  Yes this is a good site There is alot of good information that passes thur here and just like the rest of the internet its not all ture ,And I do belive that there are some regular posters that realy should keep there  fingers off the keyboard because there in over there head from the start .I would like to think that this site is a sharing Of experiance ,not someplace to babble on the keyboard.If your posting just to see your slef post take it to facebook .  Rob

[mandolinut]

Good idea with the rotating mast for both sailing purposes and possible dismasting without damaging the boat.  I am familiar with the rotating mast from years of Hobie sailing and one dismasting (with no damage to me or the boat).  Could you tell us where you found the parts to do this modification and if it was an exact fit in the mast? Thanks.

[buckaroo]

,And I do belive that there are some regular posters that realy should keep there  fingers off the keyboard because there in over there head from the start . 

Considering that your initial point in this thread was incorrect, are we to infer that you might consider yourself one of them? 

[Salty19]

Let's be men here gentlemen (apologize the ladies).

Indeed Rob is right, everyone should think before they post just like we should think before speaking. Myself included, and like Bob23 I'm sure I can recall a time or two when one of my posts perhaps a post was a bit offending-maybe not to all but certainly to some (notice the -2 Karma).   Yep, we're not perfect--thank god.

If anyone believes represented facts to be untrue,  we should absolutely discuss it as the community we are.  If you don't feel comfortable piping up in a post or sending a private message for fear of retaliation, feel free to PM (Personal Message) one of the Administrators confidentially to work through it.  Let us be the bad guy who challenges an opinion vs. fact.   This isn't our first rodeo..let us help make this place as factual and fun as it can be.

by the way, welcome Pete!  Exciting to see these boats in Oz.  I bet they are perfect for the coastal areas down there.

[Pacman]

Good idea with the rotating mast for both sailing purposes and possible dismasting without damaging the boat.  I am familiar with the rotating mast from years of Hobie sailing and one dismasting (with no damage to me or the boat).  Could you tell us where you found the parts to do this modification and if it was an exact fit in the mast? Thanks.

The conversion was easy and cost almost nothing.

I used a piece of Ipe wood for the Tabernacle.  The dimensions are 1" thick, 4.5" wide, and 6" long.

The original Tabernacle was used as a template so I could drill holes in the Ipe wood that could use the original mounting holes in the cabin top to fasten it to the boat.

I used screws that were the same size and type as the original screws but were 1" longer so they would fit into the original holes.

The pivot pin was made from a 1/2" stainless bolt that was threaded into a tapped hole in the Ipe wood with a nut and some fender washers to support the mast base.

The head was cut off the bolt leaving a short peg to serve as the pivot.

Then I made the mast base in the form of a wooden plug that has a tapered hole in it to center the mast.  The plug is supported by the original mast bolt that was used on the stock set up.

I could send pictures that would make it clear how this works but I can't seem to post them here so, if you could send me an e-mail address I could send them to you and maybe you could post them.  (Luddite here)

The whole thing is simple and works great.

Hope this helps.