F33 Main mast holding down bolts loose

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chrislloydbostock
Posts: 6
Joined: Thu Jun 11, 2009 8:26 pm

F33 Main mast holding down bolts loose

Post by chrislloydbostock »

Emma B is a 1985 F33 Cat Ketch with aluminium masts and conventional booms. I had to put off my first sail of 2016 when I found the holding down bolts on my main mast's step were loose. The mast is mounted up in the forepeak and sits on an inch thick plywood plate. A heavy cast aluminium ring locates the mast foot and is bolted through the plywood plate to the floor of the forepeak locker which seems to made of fibreglass. The 4 holding down bolts are loose and at least one can be withdrawn completely -the nut has fallen off into the void below the locker floor. The remaining bolts refuse to tighten up and I suspect that their nuts are just spinning . The problem is that it's impossible to get to the bolts underneath the mast step to tighten up or to attach new nuts as the below floor space is sealed off by a glassed in bulkhead. Judging by the mess around the aluminium ring there's been a bit of grinding going on as the mast has moved.

I'd like to pull out the mast but can't figure out how to remove the loose bolts as they just spin in their sockets. I'm thinking of cutting an inspection hole through the sealed bulkhead below the locker floor so that I can get at the bolts, but I'm wary of doing anything that may weaken the floor on which the mast sits.

Does anyone have any ideas?

Cheers
Chris

CrazyRU
Posts: 96
Joined: Fri Feb 06, 2009 4:58 pm

Re: F33 Main mast holding down bolts loose

Post by CrazyRU »

Once mast is removed there is a hole in the center of the cast ring. The hole would allow the access to the retaining bolts and nuts under the plate.
At least it is how it's done on my boat.
CR
s/v "NEMO" - Freedom 28 Cat Ketch centerboard

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Castaway
Posts: 286
Joined: Sat Dec 13, 2008 8:40 pm
Location: Lerwick, Shetland Isles

Re: F33 Main mast holding down bolts loose

Post by Castaway »

The mast comes out without disturbing any of the bolts attaching the mast step ring to the forepeak; you must, however, remove the bolt attaching the ring to the mast, the purpose of which is to prevent rotation of the mast. On my UK built boat the hole inside the mast ring is too small to reach the bolts, but there is a hole in the bulkhead below through which the bolts can be reached. Unfortunately, the inner bulkhead has to be removed to get at this, which means dismantling much of the fore cabin joinery. I don't know if the US boats are very different, although the entire internal layout is quite different aft of the forecabin. I think you will have to remove the mast as the next step, then review your options. Even a modest central hole should allow some sort of cranked spanner (wrench?) to be introduced.

Good luck.
Gerald Freshwater,
s/y 'Castaway', (UK F35 cat ketch, centreboard, 1987)
Lerwick Boating Club
Shetland Isles, Scotland

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Peter
Posts: 22
Joined: Wed Sep 16, 2009 4:12 am
Location: Bremen, Germany, UK F35 CB Cat Ketch 'Avante'

Re: F33 Main mast holding down bolts loose

Post by Peter »

Chris,
here are some pictures of the step of my main mast taken in 2011. I have a UK built (1988) F33/35 with aluminium masts. In the pictures you can detect a hole in the mast step ring near the right bolt in the foreground. This is where a 10mm (3/8in) bolt is going through the mast to prevent it from turning. There is only one of these bolts each in the foot of main and mizzen. There is no nut on the inside of the masts but a thread is cut into the wall of the masts foot. My masts are doubled at their lower ends with a tube insert.

The two holes inside the step ring are too small to reach inside the mast from below with yor hand. They are used to lead the cabling to the space below the mast step and to drain the mast as there is quite some condensation inside.

In my boat the space below the mast step can be reached by removing a piece of teakwood at the lower end of the bulkhead to the forepeak. It is just held by two screws. The opening can be seen in the last picture (by scrolling down. The mast step is supported below by a piece of plywood installed lenghtwise in the middle below the ring. This can be seen through the lower opening in the bulkhead.

A year before these pictures were taken I got a new galvanized chain for my anchor that normally rests around the foot of the mast. The chain, the mast and the mast step ring all started to corrode. I coated the ring and mast below decks with several layers of epoxy primer and the corrosion stopped.
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Hope this helps.
Greetings
Peter

chrislloydbostock
Posts: 6
Joined: Thu Jun 11, 2009 8:26 pm

Re: F33 Main mast holding down bolts loose

Post by chrislloydbostock »

Morning all and thank you very much for your help on this. Your photos Peter are especially helpful. My set up looks similar but I had no idea that the mast is actually held in the ring by a horizontal retaining bolt. Your bulkhead opening gives me the confidence to cut a similar hole to access below the floor. The last place I expected to find the answer was the Shetlands - the wonders of the internet.

Thanks again. Chris

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