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-   -   Dehler 25 Mast Compression (http://www.sailnet.com/forums/general-discussion-sailing-related/68500-dehler-25-mast-compression.html)

ianroriston 09-23-2010 04:42 AM

Dehler 25 Mast Compression
 
I have just discovered that my 1984 built Dehler 25 has mast compression :( . Symptoms being slightly loose shrouds, small crack forward of the mast tabernackle and a crack in the plastic keel casing together with a definite depresion of the tabernackle. I have no idea how the load is spread through the coachroof as there does not appear to be a support directly to the keel. This boat has a water ballast tank under the cockpit sole and forward of the forecabin bulkhead so I am sure that the load is spread over the arch of the coachroof. Has anyone any previous experience of this on this particular model of boat. I live in Spain where the vast majority of boats here belong to petrol heads and sailing is in the minority and I feel that there may be a lack of experience in the boat yards. I have emailed Dehler in Germany to see if they can assist with construction plans but not yet received a response. I have little experience in boat building but more then handy generally, not only that, a lack of cash means I have to get hands on. I am not too proud to accept any advice but do need it directly related to this boat please. Many thanks in anticipation. Ian

St Anna 09-23-2010 05:35 AM

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

ianroriston 09-23-2010 02:27 PM

Dehler 25 Mast Compression
 
5 Attachment(s)
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

St Anna 09-23-2010 03:10 PM

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)

tommays 09-23-2010 03:12 PM

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

ianroriston 09-24-2010 04:19 PM

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

knothead 09-24-2010 05:05 PM

Quote:

Originally Posted by tommays (Post 647316)
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.


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