PDA

View Full Version : mast step



willyd
04-27-2016, 02:43 PM
I am currently repairing the mast step and deck below the mast on my (fiberglass) Whitby 25. The mast step was an aluminum piece that sat on top of a large mahogany board that was bolted from each corner into the deck, through deck beams that were encased in fiberglass. Last year I noticed the bulkheads shifting around, then the deck deforming under the wooden step, so I have now taken things apart.

http://i1110.photobucket.com/albums/h451/Abuhasad/sailing%20in%20Whitby%2025/2016%20repairs/DSC02900_zpsav4y5fbn.jpg (http://s1110.photobucket.com/user/Abuhasad/media/sailing%20in%20Whitby%2025/2016%20repairs/DSC02900_zpsav4y5fbn.jpg.html)

http://i1110.photobucket.com/albums/h451/Abuhasad/sailing%20in%20Whitby%2025/2016%20repairs/DSC02901_zps74sennpk.jpg

What are your suggestions for replacing this board? Mahogany? White Oak? Cypress? Does it have to be one piece, or would a laminated board work as well? I'd like to use a local type of wood if possible, but will choose whatever's most economical.

Despite the discoloration, there seems to be very little rot in the original, but I assume I should replace it.

lupussonic
04-27-2016, 02:54 PM
If your deck beams are the main load bearing structures, I would investigate those first. Why were they encased with fibreglass? Was that to strengthen them? Waterproofing? Sounds strange to me. I imagine rainwater going down the bolt holes, damaging the beams, last owner glasses them as a quick solution. If the foot plate isn't rotten, it's not a problem, leave it and get to the bottom of this.
Is there no vertical brace going from the keel to under the foot?

Some pics of your beams would help...

Peerie Maa
04-27-2016, 03:46 PM
Last year I noticed the bulkheads shifting around, then the deck deforming under the wooden step, so I have now taken things apart.


Despite the discoloration, there seems to be very little rot in the original, but I assume I should replace it.


If your deck beams are the main load bearing structures, I would investigate those first. Why were they encased with fibreglass? Was that to strengthen them? Waterproofing? Sounds strange to me. I imagine rainwater going down the bolt holes, damaging the beams, last owner glasses them as a quick solution. If the foot plate isn't rotten, it's not a problem, leave it and get to the bottom of this.
Is there no vertical brace going from the keel to under the foot?

Some pics of your beams would help...
Just So. The mast step timber looks adequately strong. As stuff is flexing under the deck, that is where you should look.

willyd
04-27-2016, 08:25 PM
Thanks for the replies. I've already got a thread or two started over on another site (the name is a combination of "sail" and "net") about this project, so I don't want to start another one here on the repair in general, just the wood-related stuff. I ground the sealant and Cetol off of the board today, and it looks like white oak, so I'll probably go with that. Any other suggestions would also be welcome.

(But, since you asked: I can't see any evidence of the deck beams (which are encapsulated in fiberglass originally and do not have vertical supports) moving at all - there are no cracks in the fiberglass - though it's possible and maybe probable that at least the forward beam has got some water in it and some rot. I'm going to expose the suspect parts of this beam and see what it looks like.)

Junkyard Dog
04-28-2016, 10:03 AM
If the deck is deforming under the step, I think it is obvious that the deck beams are no longer adequately supporting the load. I'm surprised there is no compression post under the step.

Thorne
04-28-2016, 10:25 AM
To answer the question as asked, I'd be tempted to lam up several layers of some hardwood with epoxy for this piece. But a nice solid piece should work well too, keeping an eye open for any splitting / cracks that might be a serious issue later.

willyd
04-28-2016, 11:59 AM
Junkyard - The step sags only in the middle, between the two beams, which is also where the deck is deformed, in other words, looked at from the side, the mast step and deck sag between the tops of the deck beams, where the mast pushed down.

Thorne - how many layers is several? The step is 1 1/2" thick X 7 X 21.

lupussonic
04-28-2016, 01:08 PM
Ah, ok. So lack of stiffness in the mast plate is what is occurring. Your second picture in original post did not show up to me at first, but now that it has, I would say remake the block exactly the same size, but laminated, a sort of chunky ply if you like. Changing size will lead to rigging issues. Rebuild the same, but rot proof it, and epoxy all the way around.

Can an water get below the mast foot onto the plate?

StevenBauer
04-28-2016, 01:14 PM
I'd use Black Locust to replace that piece. Maybe even laminated up from several layers for extra strength.



Steven