Thursday, September 11, 2014

Fixing damaged cleats

Hi, this is the captain. 
This means you can expect a technical post and no underwater pictures. 
Not even a picture of me diving into murky water to retrieve a chisel I dropped overboard.

We came to the boat two weeks ago and found out that the storm caused some damage on the boat. The cleats survived 10 years of use and abuse with no major problems, but now they were twisted and the teak rail was split. 

Stern port cleat sustained minor damage
Teak rail was cracked
Bow port cleat was in worse condition
Teak rail was fully split
In reality it looked worse than on this picture
12mm bolts were bent, but fiberglass base (hull and deck) was luckily intact
Removing 40 cm section of teak
Removing original black sealant was not easy. After 10 years it was still very flexible. 
Aluminum base was installed instead of broken teak railing. This solution is a lot better. Access from anchor locker is relatively easy. Being short is sometimes an advantage. That is me inside the locker.
Work in progress: Teak is sanded and hard edges removed.
Finished cleat after repair.
When I work on a boat I usually use a lot of tools if I have them.
After we finished bow cleat we started working with the stern one.
Access to stern cleat base from below is a lot more restricted then for the bow cleats. 
This is how cleat looked before it was bent
This is how cleat looked before it was bent (from above)
Sanding off the edges of the teak railing
At stern cleat the fiberglass base was damaged and we repaired it with epoxy (sorry, no pictures).  
I wish my arm was longer. A loooooooooooooot loooooooooonger
Hmm. How on earth can I reach that far and position a nut on the bolt ?
After picture. Stern port side.
How could all this happen?

The mooring field looks similar to the one on this picture:

Each boat is tied with four lines and chain to large heavy chains, which are screwed to the bottom.
Heron was moored at low tide. 
It looked she was tied too tight and when the tide was high the lines were probably already stretched.
Then the storm came. Mooring field is relatively well protected from NE - from strong Bora winds. Also the bow of Heron is facing into prevailing strong winds. But there are sometimes short leaving storms with N wind. Fetch is not very long from N (a bit over half of a mile) and this storms are usually only lasting for an hour or so, so waves are normally not a problem.

But if you add all factors together you get this:
- Lines fixed at low tide were too short,
- Lines are oversize to protect them from chafe , so stretch was small
- High tide was amplified by strong N wind during the storm
- Wave action was violent - waves were probably short but steep
- Bow is facing NE, so wind from N or even NW hit Heron abeam to her port side
- Sails (furling genoa and main in the lazy bag) increased windage
- Solar panels, dinghy, spray-hood and bimini all increased windage even more

Lessions learned:
1) Do not underestimate the power of sea even if you only leave the boat for a week during summer in protected bay
2) Observe tide tables even with tidial range less then one m.
3)  Leave some slack in the lines to allow boat movement and rocking in the storm
4) Reduce windage if practical
5) If something held for 10 years it can still break.

Let me say at the end that original design of this Beneteau cleats was not the best. Beneteau changed the design a year later  - so they learned, but a year too late for our boat
Original design: A cleat is fixed with two 12mm bolts and goes through teak railing, through deck& hull joint, through backing plate and is fixed by nuts.
Where the bolt goes through teak railing there is a round piece of aluminum (3cm in diameter and 3cm high). That round piece is sitting exactly where deck ends, so it does not have a lot of good support.
And 3 cm diameter is not a lot to start with.
A lot of force is therefore transfered to bolts as bending force.
New design: I obtained original Beneteau aluminum parts for replacement
Instead of teak railing with 3cm hole in it there is a solid aluminum plate which is 40 cm long and as wide as the railing base (I did not measure, but it is about 8 or 9 cm). The inner side of it sits well on the deck and outer edge sits well on the hull. It is 2cm thinner than original design reducing leverage on the bolts and it is a lot stronger, as a solid piece of aluminum sits on 9cm wide base comparing to 3cm base partially overhanging hull/deck joint inside hollow teak plank.
Conclusion: It was not only a repair, this was a boat improvement as well. We will do starboard cleats in the near future.

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