Under-floor compression post

Topics primarily or specifically about the DS2. Many topics are of general interest, so please use forum sections on Rigging, Sails, etc. where appropriate.

Moderator: GreenLake

Under-floor compression post

Postby James4 » Sun Dec 11, 2022 4:41 pm

I managed to take a photo of the space between the cuddy floor and the hull, and could see that my compression post was rotted or rusted through in the middle, which was why the cuddy floor was flexing so much. I need to replace the compression post, and I'm willing to cut out the floor in front of or to the side of the mast step to do so. I prefer cutting the hole in front for several reasons. After scouring this forum for quite a while, I never saw any directions for how to duplicate or improve on the original compression post. Any ideas for materials? I'm considering a PVC or ABS coupling (2"?) shaped to fit the hull, fill with epoxy and filler, and capped with 3/4" square piece of wood or marine plywood to stick on the underside of the floor to accept the screws from the mast step But I'm open to any ideas you have. Thank you-- Jim
James4
 
Posts: 16
Joined: Thu Jul 10, 2014 7:31 pm

Re: Under-floor compression post

Postby GreenLake » Sun Dec 11, 2022 10:41 pm

Jim,

anything that will withstand 600# or more, should be fine for the purpose. The nominal tension on the shrouds is around 200#, double that and add the forestay and that is roughly the constant compression. Use a bit of a safety factor and you have the requirement.

Because the piece is so short, you won't run into complications from buckling, so many materials will have the required strength. That means, you'll be looking at two additional considerations. One would be the way load is transferred, so you need a cap on top and a base/platform at the bottom (details depend on what's already there in your boat). The other is resistance to rot or corrosion. With wood, you could try sealing it with undiluted epoxy and wrapping it a layer or two of fiberglass cloth. If you're lucky, that will seal it completely, but if it isn't sealed or not sealed perfectly, the most likely scenario is for it to rot.

That makes wood problematic to screw into, because you'd need to be sure to seal all those holes. It can be done, but it requires an extra step. There are some materials, like star board that are rot resistant. Another option would be pre-cast sheets of fiberglass (G-10 is a brand name), or you just laminate something yourself on your bench.

For the post, I think you are on the right track. A sturdy bit of PVC or ABS pipe sounds perfect. The hull is pretty solid down there, so perhaps it wouldn't need reinforcement, just good shaping for maximum contact.

If you cut your cuddy floor near/in front of the mast, one thing to consider is whether you might want to make it so you can insert a shallow rectangular pan, instead of a regular lid. That pan could be sized to fit the base of a battery, if that's something you'll ever want on your boat. Some people use these for a trolling motor, or as a source of electricity for a number of purposes while cruising or camping. Not sure that fits your intended use of the boat, but if it does, it would take care of battery storage.
~ green ~ lake ~ ~
GreenLake
 
Posts: 7135
Joined: Mon Jun 18, 2007 3:54 am

Re: Under-floor compression post

Postby W0QNX » Mon Dec 12, 2022 1:05 pm

Here are some pictures I collected of a recently cut up DS2. Pretty simple really. I don't know why you would want to cut in front of the post into the floor. The first picture is viewed from the front and would be the front wall of the front triangle area where most boats have an access thru hole now. Second is the same area from the side. Third is the mast base under the cuddy floor. Looks like some kind of old ABS type pipe to me.

Image
Space

Image
Space

Image
Space

Image
W0QNX
 
Posts: 8
Joined: Wed Sep 28, 2022 4:45 pm

Re: Under-floor compression post

Postby Alan » Tue Dec 13, 2022 4:30 pm

viewtopic.php?f=2&t=5159&p=28261&hilit=jeadstx#p28261

The link above goes to a multi-subject thread that has some photos of the underside of the cuddy, showing two different DSIIs. May be helpful to have assembled views of what's down there. It looks different from the DSII that W0QNX posted photos of, so there may have been some re-engineering during the DSII model run.
Alan
 
Posts: 756
Joined: Wed Jun 17, 2009 4:39 pm

Re: Under-floor compression post

Postby W0QNX » Wed Dec 14, 2022 6:41 pm

Alan I'll have to respectfully disagree on my pics and your thread link pics. Just like in my boat the fore area in front of the cuddy goes back under the cuddy floor for about 16 inches. That under cuddy in front of the wall area in mine is full of 3"x6" cut Styrofoam pieces running cross boat likely installed at the factory. They are in there tight and mine are fairly dry so I left them in there to maintain a "wall" between the front void area and the under cuddy void area.

Unless those other thread posters include a picture from the front showing another more forward wall then the boats are near the same in construction in my opinion. There just isn't that much area for another box if you look at the bottom picture in my post above. In that picture you can clearly see where the fore area comes down and them tucks back under the cuddy floor. A person could use a tape measure or long scale to work out the wall placements.

I can see the foam in my camera views from the front and the rear. There is no "box" but a fiberglass wall is indeed there. Even the pictures in the other thread visibly have foam just over the top of the fiberglass wall. That wall looks to me to even possibly be a leftover from the DS1 design as the 1 does have an enclosed bow area which creates a shelf like area in the front. I'm only going off pictures I've seen of DS1's as I haven't seen under one personally.

I'll upload more pictures showing the cut up boat of how the foam lays cross ways in front of a wall. My boat is the same and has that area of flat cross ways foam. If those foam pieces are 4" thick then it would be about 20" of under area going aft from the front most area (forward cuddy wall). The second picture is before the forward cuddy wall was cut out.

Image

Image
W0QNX
 
Posts: 8
Joined: Wed Sep 28, 2022 4:45 pm

Re: Under-floor compression post

Postby Alan » Sat Dec 17, 2022 2:56 pm

Now you've got my curiosity up. I look forward to seeing what you find when you open up your boat.

My boat has only a few loose scraps of styrofoam forward of the wall. Also, the views from forward and aft appear to show a convex surface, which would indicate two walls facing each other.

Anyway, my main reason for posting was to let you know that there might be structural members attached to the underside of the cuddy floor.
Alan
 
Posts: 756
Joined: Wed Jun 17, 2009 4:39 pm

Re: Under-floor compression post

Postby James4 » Sat May 13, 2023 10:07 pm

Hi WOQNX, thank you so much for sending those pictures and comments. I let the project sit over the winter. Even for California the weather was not comfortable for crawling around in the boat. I'm looking more clearly through two portholes in the cockpit floor, using a flashlight and a small mirror. I have a better view now of the connection, and it looks intact. I'll raise the mast and see if the floor still deflects. Your pictures are great. Sorry I didn't get back to you earlier. I wasn't on the site all winter, apparently.
Thank you, Jim
James4
 
Posts: 16
Joined: Thu Jul 10, 2014 7:31 pm


Return to Day Sailer II Only

Who is online

Users browsing this forum: No registered users and 11 guests