Mast step

[Mike Dh]

I'm refitting a Pearson Vanguard. The cabin has been gutted. I would like to remove the aft bulkhead for the head. would it be possible to install a compression post directly under the mast?

[Petros]

It certainly is possible, but you better get some guidance from a professional on it because the loads can be large and you run the risk of buckling the column. It is a sensitive calculation and an accurate installation is also required.

You can also consider putting in a header beam to eliminate the post altogether, but that is an even more complicated analysis and retrofit. This will also reduced the head room right where the mast is located because of the beam required.

Good luck.

[kenJ]

Google is your friend. There are several good websites and organizations that restore and sail the Vanguard. I'm sure you will find owners that have been in the same situation. Looking at pictures and the plans, it looks like a compression post would just be in the way, something to crawl around everytime you move forward. Also why remove what little privacy there is for the head? If you sail solo, not a big deal, lady guests will think otherwise.

[Mike Dh]

what I want to do is move the head to the aft port cabin. Then move the bulkhead for the V-berth aft to were the new compression post would be. Giving me a larger V-berth and head and not losing settee length. I'm not an engineer, so I don't know how to figure out the loads involved. The vanguard is a big boat so getting it right......
Mike

[kenJ]

In that case I don't think a compression post is the way to go, it will be in the way. I think you should move the aft wall of the vee berth back so it is under the mast and include a header across the the cabin roof. It will be much easier to duck under the header than squeeze around the post. You will have to make the wall much stronger than original. Sorry, I can't help with the engineering.

My suggestion would be to build the structure out of pressure treated 2x4s. Double vertical supports on each side of the opening then one or possibly 2 more vertical members outboard. Make the header out of a sandwich of 2 2x4s set on edge with a piece of 1/2" marine ply bonded/screwed in between. This is just a guess....a professional needs to confirm that it will provide enough support. they will need dimensions (header span, distance between vertical supports, etc), weights (mast, boom, sails, etc), rigging tensions, etc to make the calculations.

[Perm Stress]

Originally Posted by Mike Dh

I'm refitting a Pearson Vanguard. The cabin has been gutted. I would like to remove the aft bulkhead for the head. would it be possible to install a compression post directly under the mast?

Bulkhead do not simply take the mast compression to keel.
It also prevent the sides to to lift up relative to CL part of hull.
If you remove the bulkhead, fairly substantial ring webframe will be necessary.
Warning:
ring frame, designed "by the rule of thumb" will be either not strong/stiff enough or overbuilt out of all proportion in most cases.

[kenJ]

In my minds eye I was thinking ring frame, with framing on all sides and bracing between the vertical members. Rereading my post, I realize I didn't describe it that way.

will be either not strong/stiff enough or overbuilt out of all proportion in most cases

Guessing that the 2 bulkheads that came out are probably 3/4" ply so I'm thinking my solution is probably in the overbuilt situation. It can probably be resized after someone with the correct engineering skills determines what is really required.

[Perm Stress]

Originally Posted by kenJ

In my minds eye I was thinking ring frame, with framing on all sides and bracing between the vertical members. Rereading my post, I realize I didn't describe it that way.



Guessing that the 2 bulkheads that came out are probably 3/4" ply so I'm thinking my solution is probably in the overbuilt situation. It can probably be resized after someone with the correct engineering skills determines what is really required.

You can e-mail me if you want some assistance.