damage caused by mast compression

[jjj]

I was wondering if any of the readers could shed some light on the problem of compression damage on the bulkhead of a deck stepped yacht. The upper region of the bulkhead has stress damage very near the compression post, which to me indicates movement or overloading and the lower area of the post which meets the keel area has a crack in the laminate, is this normal movement or is there a structual problem the yacht is 17 years old. cheers jjj

<hr width=100% size=1>

 

[boatless]

Could be either, can you see any damage in the mast tube in the area of the heel fitting? That is often a fair guide to over tensioning, as are damaged bottlescrews.

What boat is it?

<hr width=100% size=1>my opinion is complete rubbish, probably.

 

[jjj]

The boat is a Hallbery rassy and there is no obvious signs of over tensioning. The mast is deck step and around the mast base there is no sign of load stressing. The area of concern is the forward bulkhead around the door frame which is adjacent to the load bearing compression post. The door frame has change shape slightly and moved about 5 mm. The lower end of the mast post has cracked the laminate which it sit near, my concern is if it structual or superficial.

<hr width=100% size=1>

 

[Robin]

If this is visible to you and enough to be of concern then the best advice would be to have a qualified surveyor look at it PDQ. The mast compression loads should be transferred to the keel directly via the mast strut, maybe it isn't and the load has come on the bulkhead. What do you mean exactly about the lower end of the mast strut cracking the laminate 'which it sits near' do you mean the bonding in of the bottom of the main bulkhead is cracked, or do you mean the hull itself under the mast strut? It is highly unlikely IMO that the rigging has been tensioned anything like enough to cause the problem per se, certainly nothing like the loads that a race boat would put on the rig with the backstay hard on.



<hr width=100% size=1><font size=1>Sermons from my pulpit are with tongue firmly in cheek and come with no warranty!</font size=1>

 

[jjj]

The mast strut has cracked the laminate just forward of the area which it's sit on, I would assume that this is the hull and the compression loads are transfered directly on the the keel.

<hr width=100% size=1>

 

[claudio]

Is it possible that the yacht took a severe grounding and the compression post transferred the forces upwards towards the deck ?



<hr width=100% size=1><A target="_blank" HREF=http://shop.yachtronics.co.uk>http://shop.yachtronics.co.uk</A>

 

[Robin]

The loads SHOULD be transferred to the hull, without cracking it, it sounds as if the bulkhead is taking some load now which it shouldn't, hence the door frame distortion. Has the boat hit anything/run aground hard perhaps to account for cracking around the front of the keel/mast base? As I said this is a case IMO for a qualified surveyor to check it over as anything else is pure speculation I'm afraid.

<hr width=100% size=1><font size=1>Sermons from my pulpit are with tongue firmly in cheek and come with no warranty!</font size=1>

 

[boatless]

I was sitting doing the crossword at the pub, and stuck for inspiration, came up with the same thought. But, and a fairly big but at that, for the forward end of the keel to come up would mean an unlucky bounce or hitting something while going backwards... I've seen broken keel floors in grp boats, always at the back end of the keel.

<hr width=100% size=1>my opinion is complete rubbish, probably.

 

[claudio]

Isn't it possible that the damage could have occured by striking a submerged rock?
Doesn't it depend on the type of keel and the type of impact?
If the HR has a fin keel with a raked leading edge, I can see that this sort of damage could happen.
Just a thought, I'm no expert , as mentioned by a previous poster, the damage needs to be professionally assessed. There could be a severe structural problem with the vessel.

<hr width=100% size=1><A target="_blank" HREF=http://shop.yachtronics.co.uk>http://shop.yachtronics.co.uk</A>

 

[Aja]

Is the bulkhead forward of the mast step? Do you have a babystay? If so this could be over tensioned and have pulled the coachroof forward of the mast step up resulting on cracking and a gap between the top of the bulkhead and the cabin lining.

Saw it on a boat recently. Released the tension on the babystay and a couple of days later the coachroof reverted back to its original shape.

No indication of problems with the mast suport either at the keel or coachroof.

Just a thought.

Donald

ps Caps and lowers were fine for tension.



<hr width=100% size=1>

 

[oldsaltoz]

G'day tripple J,

Your profile does not tell us what sort of yacht you have, it would help us all and you if you could provide a little more information.

There are 'some' brands of yacht that are known to have the problem you list; the fix for one well known brand was to beef up the bulkhead above the opening after inserting a filler strip.

But without more info we are all guessing to some degree.

Avagoodweekend....

<hr width=100% size=1> Old Salt Oz /forums/images/icons/cool.gif Growing old is unavoidable. However, growing up is still optional.