Mast Beam Reinforcement

[jeffthogmartin]

Hello all, my girlfriend and I have just purchased a new to us albin Vega. The mast beam is in pretty decent shape, although there may be a very slight compression of the deck on the port side as I can see a very small gap between the top of the beam and the cabin roof when looking at the forward side of the beam. The starboard side seems to be snug against the coach roof. In addition both supports are not touching the cabin sole, although the port side support is a little lower than the starboard side. Also, the head door had closed just fine when I originally viewed the boat before purchasing and the rig had been down. Now with the rig up and tuned snugly, not overly tight at all, the head door hits on the false beam (plywood piece with veneer). With the false beam off the door closes just fine and there is a gap between the top of the door and and the mast beam. This gap is an even distance across the width of the top of the door. Therefore, I feel like the beam is in pretty good shape, but would like to reinforce it as a preventative measure. I have a few questions about the procedure. I know this as been beat to death on this forum, and i have reviewed a lot of the previous posts on this subject but I would like a little more clarification. My questions are as follows.

1. Does the small gap between the deck and beam on the port side mean the deck is compressing? Or could the mast beam have shifted downward from an impact or big accidental gybe or some sort of other one of event.

2. I'd like to re-inforce the beam with Steve Birch SS kit, are they still available?

3. If the kits are not available I could also reinforce by using the false beam as a template and having a machine shop cut the stainless piece for me. I am aware of the general procedure but What are the detailed procedures like? Does anyone have Steve's step by step instructions they could upload?

4. In Steve's kit was there a thin SS piece that fits between the reinforcement and the roof? If so what are the dimensions of this piece?

5. It would be easier to show the gaps I am talking about with pictures. Is there a way to post pictures with my original thread on this group?

Thanks in advance for any help anyone could offer.

Jeff
S/V Allegro hull # 1240

 

[jam9991]

I used a 1/4 aluminum 7075 plate that can be cut with a saber saw it has excellent strength characteristics close to SS but you can work it yourself IMO the real problem is that the main bulkhead needs to be 3/4 inch. But that's a major job my main bulkhead had delaminated so I replaced it with 3/4 with the stock bulkhead I would have put a 1/4 12 inch 7075 aluminum plate fore and a1/4 7075 aluminum plate aft between the bulkhead and the mahogany beam. That gives you a 1/2 inch of aircraft aluminum laminated beam 5/16 thru bolts hidden from the cabin by the mahogany beam through aluminum sheets and bulkhead apply a teflon grease to SS bolts to isolate from the Al. You can do it yourself I also put a thicken epoxy applied with a caulking gun between the beams and the underside of the deck. polysulfide caulk may also work. the white paper on the topic is a good read Best of luck Sent from my iPhone

 

[alaskaflyfish]

Sorry I took so long to reply to the mast beam reinforcement question. Most everything you need is in the picture album on the group site. I found the best installation of the the supports were with the mast down so the vessel could take on its natural shape. I would buy two kits from Steve Birch (good quality and inexpensive) and thru bolt them fore and aft. Forget about cosmetics, go for strength. Additionally, add diagonals to the bulkheads to reduce buckling and twisting. Increase the bulkhead bolts to 1/4 inch and add doublers to the lower portion of the bulkheads (under the settees) to increase the bulkhead foot print to the hull. Fill any gaps between the beam and cabin roof thereafter with epoxy compound of your choice. The s/s strip in the kit is about an inch wide and about .060 thick if I recall correctly. And while your at it get a folding mast step form Ballenger Spar, its an excellent piece of kit. Not a difficult job, good luck.

 

[vega1860]

If the deck is depressed, I would ask "What supports the deck". Is it the beam?

If the beam is out of position I would ask "What supports the beam?"
Is it the upright posts? No, they do not reach the cabin sole. The
posts are attached to the bulkhead and serve as trim and possibly stiffeners.

The bulkheads are connected by and support the beam. The bulkheads
are in turn bolted to fiberglass tabs on the inside of the hull.

The beam connects the two bulkhead halves, transmitting the stress
downward to the tabs. Is the hull bulged outward where the bulkhead
is attached? This has been noted on some well used Vegas. The design
is intended to transfer the stresses of the rig to the hull.

My opinion (One of many) is that the problem is caused by the
manufacturing expedience of bolting the two-piece bulkheads to the
tabs rather than glassing them to the hull, not by any weakness in
the beam. I think that reinforcing the beam is probably unnecessary
and, without due attention to the bulkheads, would be futile.

"Fair Winds",

Chuck

 

[alaskaflyfish]

Chuck, I agree with everything you stated, however..I noted a compression failure in the wood grain on my mast beam. They can be difficult to see to the untrained eye. I inspect aircraft wood wing spars as part of my aviation business. This compression of the grain leaves the beam in a diminished state,which also suggests it is under a heavy load while transferring stress to the hull via the bulkheads. Also, using a straight edge on the bottom of the beam you will notice the beam is banana shaped when under load. I also noted the slight bulge on the outside of the hull directly under the bulk head, hence the reason for adding a doubler to the lower bulkhead (3/4" marine plywood)under the settee to increase the footprint of the bulkhead thereby decreasing the psi stress to the hull. Pictures can be seen of this mod in the photo album site. I used thickened epoxy to fill that gap for a exact fit. Adding the diagonals also decreased the twisting and flexing of the bulkhead that the doorposts were incapable of resisting. The rig is now adequately stiff without having to do a major refit.

 

[Vega1447]

I agree with all that Tim and Chuck have posted.I replaced the (?) teak mast beam with a new one double the thickness, also fitted one of Steve Birch's stainless steel plates on the forward face of the mast beam. Finally I fitted a second thickness of top quality marine ply to the two bulkheads
- doubling the thickness of course - and fitted diagonal struts on the aft face of the bulkheads. The struts and doubled bulkheads were through bolted.I've posted photos here and can repost.All the above jobs were done in sequence over maybe five years, not all at once. I believe that this (?) final solution is very strong.I think the comment about the importance of the bolting of the lower parts of the bulkheads to the tabs in the inside of the underwater hill is very true.
Do people believe that these tabs should be doubled (so gripping the lower parts of the bulkheads on both forward and aft sides) or permanently glassed in?John V1447 BreakawaySent from
TypeApp

 

[alaskaflyfish]

In regards to tabbing let me backtrack for clarity. On the original setup the bulkheads terminate at the tabbing not making contact with the hull, leaving only the narrow portion of the tabbing to transfer the load stress to the hull. If you fill the gap between the original bulkhead and the hull with thickened epoxy then both the tabbing and the bulkhead transfer stress to the hull on a wider footprint. Then if you add an additional doubler (3/4") to the lower portion of the bulkhead and epoxy fill that gap, then the tabbing, original bulkhead and the new doubler transfer the stress to the hull over a wider area therby decreasing the point loading and reducing the bulge effect on the outer hull. To create new tabbing on the opposite side? Its a good idea but I have not yet done it. However, I probably will now in the next few weeks since you mentioned it.

 

[jam9991]

Here's my 1 1/2 of 2 cents. I had to replace my main bulkhead because the previous owner cut 6 in speaker holes in addition to water damage and delamination I don't know if my boat had been previously modified but my 1/2 inch plywood bulkhead had putty all around the edge transferring the load directly to the hull I presumed that was standard The two bulkhead were connected with a short "beam" that fit into a recess in the bulkheads across the door. A 1/2 mahogany beam was foreword and the 1 1/4 mahogany beam aft. These were fastened with # 12 bronze screws. There was putty between the bulkheads, forward beam and deck so force went deck - putty- bulkheads and beam over door - machine screws to tab and putty- to hull. After discussions with John K , I installed a 3/4 bulkhead and put putty between everything I also added another tab aft at the hull as was recommended in the paper on the mast beam. This gives 4-6 inches of load distribution at the hull. Also at the deck there were 1 inch plywood braces screwed to the deck with # 10 bronze wood screws ( possibly brass) to stabilize the fore and aft movement of the bulkheads st the deck I've never inspected another Vega so I would be interested if what I found was standard. Also my understanding is the the door trim reinforces the bulkhead stiffness but does not directly support the mastSent from my iPhone