Hello Ian,
Could you sent some pics of the depression and crack.

Often, what appears to be too big a job, is best attacked one step at a time. Some one here on SN will have the experience and advice to help.
regards

 

Thanks very much for the pictures advice and I have taken some for information. They show the mast tabernackle and the gantry that leads off to either side, close ups of the tabernackle and the keel case inside the saloon. I would say that the compression is 3/4 mm maximum. Hope this helps, Ian

 

Dehler may be the best people to talk to as this may have happened to your model in the past.

Cause:
Has the mast moved either forwards or backwards due to overzealous tensioning of the forestay or backstay? Is there any flexing of the bulkhead or a 'creaking' noise from the bulkhead on a windward beat?

Fix:
Ok, from what I can see in the photos, you have to take the mast down, remove the tabernacle & headlining and find out what has moved. You will then need to reinforce the decking and possibly the footing or integrity of the bulkhead.

This would be done by a mixture of epoxy and something akin to a group of chainplates to the tabernacle.

I am glad you noticed this when you are tied up to a marina, not in the middle of the atlantic.

Step by step and good luck. Please post your progress (with pics)

 

I Would guess that what ever wood was used under the mast area in the core has gotten wet over time and turned soft

The cure will be to cut out and replace

 

I Would guess that what ever wood was used under the mast area in the core has gotten wet over time and turned soft

The cure will be to cut out and replace

That's exactly how it appears to me too. Seen it many times. A good fiberglass guy can fix it to where you would hardly notice.
That's not to say that the whole house hasn't sagged a little bit too. Boats are soft.

 

I'm pretty sure that as there is an absence of a mast compression post that the load is taken up by a ring beam spread through the coach roof to the hull. The bulkhead between the saloon and the V berth for'd is certainly not load bearing and a bukhead only exists on the starboard side. The portside is open access to the V berth. The keel case is simarly not load bearing. I am hoping that Dehler will respond to my email request for construction details. I can find no previously reported problems of this nature with this model. The boat is a Van de Stadt design and this guy was no mug. I am beginning to think that it is water ingress into the wood immediately below the mast via the screw holes that hold the tabernackle to the coach roof, probably marine ply but I am unsure just how intricate the replacement will be if it is a ring beam and the integrity of the structure is to be preserved. From previous research I learned that these boats were built to sail in the Baltic and considered to be sturdily and well constructed, just got unlucky I guess.
The forestay is not adjustable but the backstay is. Thanks for your suggestions so far, Ian