Flex in cabin roof (563)

[Steve]

We had a testing day of sailing Boxing day on Geographe bay , winds from 15-21 knots made hard work as we sailed very close to the wind to reach our target destination .
We finally anchored up at Siesta park for some lunch, swimming/snorkeling and more sunburn .
We departed Siesta Park with a wind change and I decided to beat hard along the shore then heading out to round the Busselton jetty, with a 2nd reef in the main and a storm jib it made beating all the way back to port Geographe a nice comfortable sail.
Excessive weather helm was on the menu for the day, embarrassingly rounding me hard into the wind on one occasion, bought about through poor sail trim from trying to nurse the rig. Its like cabin roof compression was a non event for the day scoring a 3/10 ---- aching tiller arm, massive rudder pintails loads and sore sheet adjusting arm/ shoulder scoring an 8/10!!! taking it for the team.
All thing said, I love the way the hull sailed and I can't wait to fix the mast compression, get confidence in the rig and really sail the boat.

Steve

[Yara50]

Steve
Back to your shroud supports- it would be a good idea to check the stainless where it passes through the deck- crevice corrosion at these places is a classic problem.

In heavy weather helm maybe ease the traveller and/or pull the c/board back a little bit.

[Steve]

Hi Ian,
I'm going to remove the stainless and replace them with a slightly different design . The problem with the ones on there at the moment is they flex at the point where the angle changes from the side of the hull--- to the mast to form a crease point. This crease is stressed even more due to the two turnbuckle forks and pins jamming together in the "y". When you stand the mast up you need to be careful that the turnbuckles are carefully positioned so that the shrouds are pulling straight through the center axis of them. With the mast stood up, no amount of wrestling can free them if they jam, so loosening them by lowering the mast slightly is the best option to free them. Seeing there is flex along the crease, there is a high possibility of tiny cracks and corrosion goes hand in hand with fatigue cracks.
With regards to the weather helm , I had the center plate right back and had adjusted the traveler lo leeward. The draft in the sail was clearly aft and the sail really needed tensioning to bring the draft closer to the mast. The jib needed sheeting right in and tensioned harder on the halyard but I chose not to go tighter being mindful of the mast mount. I really don't think the weather helm is an issue , sails where just badly unbalanced.

[Yara50]

This design looks like it was made for a conventional upper and lower shroud rig. Any sign of that on the mast?

Ah, now that I am looking at your picture on a full size screen, I can see the two turnbuckles. They are meant to mount individually with shackles through each of the holes in the plate. Done that way, the loads should then be more axial along the plate, with minimal deflection.

[Steve]

Got started on some digging, grinding and glassing, one of my boys had a few days so spare so he got in and did the real dirty work for me, what we found was interesting. Unfortunately what we found was that the arch way had only been attached to the roof only with rivets and all the rivets along the top of the arch had sheared. The filler that is seen to have cracks in it was the only bond between the roof and arch way (along with the flowcoat). The base of the arch way that had also cracked was ground out and I filled the void with epoxy. I must also point out to take note of the holes that have been cut into the arch by previous owners that are destroying the integrity of the mast support arch, these holes are home to speakers and a car radio

We also stood the mast up and heaved on the halyards and stays to measure the flex and to isolate the point that sees the most deflection so we could go about reinforcing the roof. We decided to build another arch way forward of the mast plate

[geoffr]

Steve:

Great work here by you and your son.

I had a similar problem: the rivets and self tappers had all sheared under the flexing stresses, so that the roof basically floated up and down with little hold or support from the arch.

Your fix looks strong; how is it performing now?

I also resisted the temptation of cutting further holes through the arch for speakers, as I decided this would also weaken the very point of having the arch there in the first place. Instead, I mounted some computer speaker on angle brackets off the arch wall, and they work a treat.

Cheers,

[Steve]

Thanks Geoff,
our modifications worked well ,my son Kev has been a great help and without him, I would have only been able to do an hour or so a day on it.
We proceeded to drill out the broken rivets from around the original arch way and right down the starboard side, we gave the arch a good thumping to get some separation. The rivets on the port side were still in tacked but only because the bottom fastening of the arch had failed. We then masked up the bottom seam and injected epoxy in the spaces between the rivets then followed the injection around popping off the new rivets, very messy but extremely effective. Epoxy dose seem to clean up allot easier than polyester resin though. We also injected epoxy into the space between the roof and the new archway to fill any spaces that where created from a non perfect fit, I drilled a small hole through the top of the roof above the archway to bleed out the air and epoxy.

The mess

Friday was our test , taking the 563 to Perth and launching at Woodman point. Standing up the mast we found that the forestay was now too short and the cabin roof was rockhard. Changing to a longer turn buckle fixed that problem and even the side shrouds have a twang when you pluck them.
The wind was every where that day becoming becalmed on several occasions,,,, too having to put a reef in the main only to be becalmed again in an instant,,,, and then 10min later being blasted home by the Fremantle doctor, By the time we got the 563 on the trailer the sw wind was at 27knots.
The cabin compression seemed non existent, leeward shrouds where only slightly loose when heeling,(you had to feel them to notice) . Weather helm when heeling was still apparently strong , I was able to flatten the sails much more and play around with the centerplate( the thrust washers I made for it stopped any clanging) and also the traveler, but the yacht still wanted to aggressively point up at the first sign of heeling. Hmmm, I seem to have to put allot of tension on the main halyard for little seen effect along the main luft, halyard rigging might need some inspection. Also now that the roof is no longer flexing , the extra length required for the forestay would lead me to believe there is more aft -rake on the mast now.
All in all another great day on the water ,sailing in the shipping lanes of Cockburn Sound and out to Carnac Island and back.

[geoffr]

Great work again Steve by you and your son.

The results seem well worth it.

I like the deck colour of your boat too (it's the same as mine).

Cheers,

[Andrew]

"Teria" has quite a bit of cabin deck flex in between fore-hatch and mast-step. noticeable when you walk on it, it doesn't seem to affect the mast support beam system in any way. The deck must be a composite sandwich , not sure what the core material is but its probably crumbled or rotted. the holes in deck are sealed where old fitting bolts once resided.

I have learnt to live with it but it does worry the crew. Wonder if epoxy resin can be injected into the holes to create a bond between the two outer fibreglass layers, not that keen to do any open heat surgery on it just yet.

[Ozzie]

http://www.trailersailerplace.com.au/ph ... ilit=Balsa

There is some good advice to be found back in the archives of tsp Andrew on this subject.
I like advice when it's offered in the framework of "this is what worked for me", in good spirits without judgement from some folk as above . There is a few good suggestions on repair to soft core in a composite deck.

Reading this again I hope I never have to do it. But I think I might try coming in from the top and diguising the holes with the non slip areas . Big job anyway.