Rigging too tight - Mast compressed deck!

[mikebikeboy]

I've been sailing this 27 foot Cape Dory a few times and noticed sometimes while heading into the wind the jib would sort of "pump" and I figured the backstay / forstay were too loose so I tightened the backstay quite a bit. It did seems to help the issue but not entirely.

Today I go to the boat and noticed inside the cabin just below the deck-stepped mast I am seeing a slight bulge pushing down on the liner. I don't remember this bulge before, so I'm guess it's because of tightening the backstay too much.

I loosed the backstay and am hoping the deck returns to normal. I think at most it might have moved 1/4 inch.

Did I just destroy my boat? Not sure how to feel right now....

I've just ordered a rigging tensioner so I can get it right instead of guessing...

I'm an idiot!?

[markwesti]

It happens to even the most stout built boats . And no it wasn't your fault . Up for a little work ? The mast needs to come off the boat and you need to rebuild the deck (at the compression area) and you need to look at the compression post , to start . Also if it were me I would get together with your owners group , I'm sure it has happened before .
Don't worry be happy .

[Jammer]

Probably more due to softness in the deck than overzealous tightening.

[Chotu]

No problem at all. This happened on my first boat.

Just loosen the mast until you can get the dent to pop back out. Then put a compression post inside, under the mast to keep the deck from deforming again. Tighten it back up as much as you like it and it’ll work just fine.

[JPA Cate]

Fwiw, I think a look at the owner's group is a good idea. For some boats, there are groups of known problems with known solutions.

I would look at the compression step at the mast base if it is keel stepped, or at the deck, if the decks are known for getting soggy. All is fixable, but some is easier than others. Have had friends have to start at the keel and work up to fix such a problem. It depends on how your boat is made.

Ann

[Don C L]

I had to rebuild my mast support under the deck for my mast. It originally was an arch of laminated plywood wrapped in glass spanning the bulkheads. I am sure it was plenty strong when first built, but over time it was weakened and water damaged, and sagging, but still sailing! Mine now is pretty strong, it supposedly will hold 10K lbs which is about 4000 more than it will need (supposedly.) But I have noticed that while sailing under a good strain and boat pitching I can feel the deck and mast support arch flexing a bit when I put my hand on it. Also, I too tightened up my backstay last time out and while it is tighter, my hanging locker door doesn't close as easily now. So, no I don't think you have destroyed your boat but I'd say building an arch under the mast spanning the bulkheads may be a good idea for your boat too (which is similar to mine,) or some other strengthening solution. Is there any rot under the bulkheads or that post nearest the center? Tabbing still good on the bulkheads?

[TrentePieds]

Normally boats are designed so that the compression loads from the mast are taken by a bulkhead that vectors the loads into the hull. This bulkhead, in a 27 footer, would be either the one forward of the toilet room or the one aft of it. All the Alberg designs, of which yours is one, employed, AFAIK, this method.

Sometimes it's necessary to strengthen the bulkhead by marrying a post to it. This post would then take the loads straight down to the keel and it would be integrated with the cabin layout so that it appears to be part of the door coaming for the door that closes off the toilet room.

But if, from within the saloon, you can see the deck sag, this is not likely to be the way your boat is arranged.

If, for whatever reason, that particular arrangement cannot be used, a mast step consisting of a weldment may be placed on deck in such a manner that the ends of it rest on deck immediately above the two bulkheads that are typically 30 to 36 inches apart. That obviously splits the total compression load in two so each bulkhead only has to carry the half of it. The mast step has a channel section to prevent its sagging.

There are lots of ways to fix you particular problem, but the first thing you gotta do is take some accurate measurements so you know with certainty just where you mast stands in relation to these two major bulkheads.

Close your companionway hatch to give yourself a reliable datum. Then from the after edge of the hatch measure accurately the distance to the after side of your mast. Then measure from the after side of the hatch to the after side of the after bulkhead and lastly measure from the after side of the after bulkhead to the fore side of the fore bulkhead. You are now in a position to draw a dimensioned sketch to see where you mast really stands, and to evaluate what you may have to do to remediate the sag in your deck.

So despair not! The problem is fixable :-)

TrentePieds

[Tillerjockey]

tap the deck with the back of a screwdriver. If you get a sharp sound, the deck is ok. It might have moisture but it's not delaminated. If you get a dull sound, the deck has started to delaminate and repair will be necessary at some point. You can put a floor jack underneath as a temporary support, until you get around to doing the repair. Maybe just some extra support for the deck in the cabin. It's a great boat. Enjoy it.

[africanmarco]

A common problem of the Albin Vega. You'll find suggestions on the Vega forum.
Fair winds

[jim King]

It sounds like your compression post may be failing. Any water coming in around the compression post? I had a similar situation and when I pulled my mast I found the compression post had rotted out around the base and needed to be replaced. Which we were able to do with an $80 4x4 of pressure treated pine. You may need to jack up the arch on your ceiling before inserting the new compression post.

[mikebikeboy]

This boat uses bulkheads as compression posts, there is no dedicated compression post, such as a metal pole.

when I go to the boat in a day or two I'll try to inspect the bottom of the bulkheads to check for rot

thanks for the helpful tips everyone, I'll be studying all the suggestions and will report back with any findings!

[garyfdl]

You're (probably ) not an idiot and no, you haven't destroyed your boat.

I'll go out on a limb and say this is a common problem on vintage boats with deck-stepped masts and cored cabin tops. I had the same problem on my old Cherubini Hunter, to the point that the cabin top cracked at the front edge of the mast step.

Can you/how to fix: It is DYI-able, and the advice given by other members so far is good.

My suggestions (based on my boat):

Topsides check the mast step and surrounding area for cracks. and cabin top penetrations like the wiring/connector for the mast lights and antenna. You're looking for any way that water can get into the core. You can sometimes tell by tapping on the area with a 'soft' (brass or hard plastic faced) hammer. It the sound you get is a sharp 'tap' you may be OK. If it is a dull 'thunk' or 'thud' it's probably wet. If you are OCD like me, you drill 1/4" holes under the mast step and around the surrounding area, checking for wet core. If you don't find it GREAT!!! Inject thinned epoxy into the holes to saturate the core as much as possible and "tighten up" the area where mast steps, then fill the holes, fair, and paint.

If you do find wet core... you have some decisions to make.
1. Sell the boat. Yes, I'm serious. Repairs of this nature may be beyond what you are capable of and can be expensive when done by the yard.
2. Live with it. But know you have lost or will lose the structural integrity between the overhead and cabin top, and that it will, eventually crack in the area of the mast step.
3. Repair it. If you DIY this can get pretty involved. It could be anything from drying out the area under the mast step and injecting epoxy to removing a portion of the cabin top and replacing everything under the mast step (which is what I did on the Hunter. if you want further details PM me. It's too lengthy to post here).

That said, you can also:

Add a compression post and maybe a beam. I made a post of 1-1/2" thick wall aluminum tube, with 4"x 4" x 3/8" thick aluminum plates welded to the ends. Plates had 1/4" countersunk screw holes in each corner, so it could be securely attached to the overhead and cabin sole. Vent holes were also drilled in the center of the plates so pressure could escape from inside the tube during the welding process. I made a bearing beam that ran athwartships across the cabin top our of a scrap piece of cedar 4x4. It was a little putzy (lots of sanding, fitting and sanding some more) getting it to match the cabin top curve, but do-able.

Check under the sole where the compression post will sit. Make sure it is sound. If there is airspace beneath the sole where the post will sit, that has to be filled in for support so sole doesn't deform. Pressure treated scrap can be used, with the grain vertical is best (wood is has better compressive strength with the grain vertical). If the treated wood is dry (generally meaning a year or more old) I would epoxy the snot out of it (i.e. multiple coats or soaking) using thinned epoxy so it penetrates, paying particular attention to the end grain. That way it should last forever.

Installing the post and beam was a two-man operation. With the help of some duck-tape (the handi-man's secret weapon ~ credit to Red Green and our Canadian cousins), one person holds the beam in place. We then used a couple jacks and posts to apply pressure to the beam, until we could slide the post underneath. We "eyeballed" it plumb (the boat was in the water/doesn't sit level), removed the jacks and screwed the post to the beam and sole. The beam was not attached and stayed in place due to compression.

[holtjp]

If you read "The Rigger's Apprentice" by the late Brian Toss, you'll be surprised by the amount of tension he recommends for the shrouds. I believe the figures are 15% of the rated breaking strength of the cable. Based on conversations with friends and boat yard mates, I would bet most rigs are under tensioned. In light of the recommended tension figures, the advice on reinforcing your boat's mast step are spot on.

PS: I use the Spinlock tension gauge and find it to be much more consistent and repeatable when it comes to measurements.

[Marathon1150]

Our Beneteau Idylle 1150 had a known issue with the compression post step sagging. The pre-purchase survey showed no problem but about 6 years later after sailing to Mexico, and several days of seriously heavy weather off of California, the step failed and everything sagged. Though to be fair, at least a partial cause of the failure was the holes drilled through the step by both Beneteau and a previous owner. The step contained a teak block which became saturated with water while we were away and the "dripless" shaft seal leaked and filled the bilge with water.

We rebuilt the step with triradial fibreglass cloth and epoxy resin, drilled multiple holes in the deck near the mast after jacking it up inside the boat (after removing the compression post) and injected the holes with very thin epoxy designed to saturate wood and restore its strength. Five years later all is good.

BTW, a boat neighbour tensioned his rig with a gauge using Baba 30 factory specs and discovered afterwards that he could no longer open or close cabin doors. As others have suggested, probably best to seek a consensus view on the most appropriate tension before re-tensioning again.

[dfelsent]

When I raced semi seriously the backstay tension was up and down all the time. Upwind, downwind, light air or heavy air.
The tighter backstay tensions the forestay, flattening the jib. Even on my Sabre38II with a masthead rig the additional mast bend would flatten the main quite a bit too. Separate fore and aft lowers with a keel stepped mast helped make that happen.
One of my checklist items when leaving the boat way “backstay eased.”
Btw, on that boat I had sails and rig tune set up so the main and jib flatness and fullness played very well together. It was a dream going upwind.