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Deck repair advice

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Created by Microbe > 9 months ago, 25 Sep 2020
r13
NSW, 1427 posts
7 Oct 2020 8:07PM
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Ok thanks Microbe. Top plan to set everything right.

That strap installed is on the right track but it is very poorly executed as you allude to. It should be under tension and taking the cap and diag shroud load down to something solid but it is doing neither sorry to say. Why it is bent like that can be guesstimated but let's go forward to the solution. The single bolt through the topsides at the lower end of it is no good and needs correcting.

Without doing a rig calc on your boat I would suggest that the input from your SS22 owner contact is probably correct - and it is against normal intuition I agree - but the issue is that maximum load in the standing rigging depends on the initial set-up tension and elongation from zero load in that stay, and the added deflection compared to the original loaded stretched length, from that state when under load during sailing - the worst load case being the knockdown to 90deg due to whatever reason. So for the ss22 rig the diagonals have about (say) 3/8 the true length of the caps - but under the worst case load case their relative extension would probably be more than the caps - so the extension divided by the original length which is strain and hence proportional to load, will be more. There is more to it than this but it is hopefully a reasonable answer.

To get to your solution - totally agree - see my real bad mudmap of the suggestion for;

Item 1 - the 3 bend chain plate flat bar which is bolted to the cabin side and the inside flatbar strap item 2. 3 bolts items 1a, 1b, 1c. Bends in stainless flat bar are not usual but if they are done carefully with a smooth radius they are a lot better than welds. Bolt size to be sorted.

Item 2 - the flatbar strap with 4 bolts 2a/b/c/d. Bolt size to be sorted.

Item 3 - the ply gusset as you mentioned. Epoxied into the original structure, probably 16mm, good fillets and glass each side.

Item 4 - the saddle for the diags, 4 and 4a,b,c being the saddle, bolts and underdeck ss plate all of suitable scantlings and suitably connected into the ply gusset. The connection into the ply gusset with the 3 bend chain plates and strap 90 deg to it needs sorting.

Of course please advise of any clarifications needed and pass this across your ss22 owner for his comment so this can be optimised as regards effort, time, cost, but still get the result you need.



Jolene
WA, 1554 posts
7 Oct 2020 6:11PM
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Lowers usually take more load because they have a more acute angle to the mast. If you look a older IOR boats especially ones with single inline lowers, they usually have heavier lowers,,, just like my boat

Microbe
WA, 166 posts
7 Oct 2020 10:07PM
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Wow! Thanks r13. That's an amazingly detailed plan.

In your diagram do the cap shrouds attach to 1 - the flat bar on the cabin side? That would put them a bit inboard of where they currently are. Also, currently they are in line with the mast with the lowers astern of that position. Not sure if your plan brings the caps back or the lowers forward?

One point to bear in mind is that the Swan River has three bridges near Fremantle that require me to drop my mast in order to transit. Having the caps in line with the mast, and having a connection point in line with the mast pivot bolt helps keep some tension on the stays so the mast doesn't flop from side to side.

Thank you so much for all your suggestions and sharing your knowledge. I really appreciate it.

r13
NSW, 1427 posts
8 Oct 2020 12:22PM
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No problem, good to be able to assist. Yes caps to 1. Ok good point best to have the 2 shrouds located where they are now.
See below have added sketch (not to scale) top left with possible arrangement - this is a cross section through the new bulkhead and deck on port side showing the caps ss flatbar forward, and diagonals ss flatbar aft. The latter has 2 careful bends so as to get the take off point located where it is now. The hatched item is a hard timber wedge - say spotted gum epoxied securely. At least 3 bolts through both straps. Need tapered washers under the upper 2 nuts on the aft bent diagonals strap. On Sunday I will measure the ply bulkhead thickness on the Col22, also the bolt diameters and ss strap thickness, width and length. SS22's are a bit heavier overall than C22 (but a bit lighter keel) and deeper draft than C22's - displacement 1200kg and 998kg respectively, keel 408kg and 499kg, draft 1.22m and 0.97m. SS22's will probably have a bit higher righting moment.



Microbe
WA, 166 posts
8 Oct 2020 9:37AM
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Thanks,

I was considering something like this - sort of a combination of what you're suggesting and what the other SS22 owner did.

I'll glass a ply semi bulkhead under the deck and run a stainless strap along either side. Chainplates will be saddles on either side of the deck on the same bolts. Then I'll run a turnbuckle from the saddle to the strap. I could also run a strap down the front of the ply and bolt it to the same point on the hull as the existing one for additional strength.

I'll put a stainless strap on either side of the ply and then could have two turnbuckles - one attached to the lowers and one to the caps.


r13
NSW, 1427 posts
8 Oct 2020 2:14PM
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Ok that looks great - there are numerous ways to do this.

r13
NSW, 1427 posts
11 Oct 2020 4:31PM
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r13 said..
No problem, good to be able to assist. Yes caps to 1. Ok good point best to have the 2 shrouds located where they are now.
See below have added sketch (not to scale) top left with possible arrangement - this is a cross section through the new bulkhead and deck on port side showing the caps ss flatbar forward, and diagonals ss flatbar aft. The latter has 2 careful bends so as to get the take off point located where it is now. The hatched item is a hard timber wedge - say spotted gum epoxied securely. At least 3 bolts through both straps. Need tapered washers under the upper 2 nuts on the aft bent diagonals strap. On Sunday I will measure the ply bulkhead thickness on the Col22, also the bolt diameters and ss strap thickness, width and length. SS22's are a bit heavier overall than C22 (but a bit lighter keel) and deeper draft than C22's - displacement 1200kg and 998kg respectively, keel 408kg and 499kg, draft 1.22m and 0.97m. SS22's will probably have a bit higher righting moment.




Columbia 22 measurements today as mentioned above that I would advise. See 2 photos below.

Ply bulkhead thickness 15mm.

Chainplate bolt diameters 5/16". 3 bolts per chainplate. A bit light imho. Would suggest 4 bolts at least, and 3/8" diameter. Also as per the photo the shear loading in the bolts is going through the threaded portion of the bolt which is a big no no for single shear joints - the shear loading must be going through the unthreaded bolt shank for a single shear arrangement like this - the other side of the bulkhead is the head of the bolts with washers as per prior photo - the bolts should have been inserted from this chainplate strap side.

Chainplate total length 300mm (240mm below deck level), width 32mm, thickness 4mm. Again imho a bit light. Would suggest 50mm wide 6mm thick. Suitable length for the 4 bolts.

So these are from the Col22 ~1975 build. For your SS22 as above I would beef these up a tad including 16-20mm certified marine ply for your semi-bulkhead infill gussets. A few grams extra weight here for assured strength is well worth it. Seems like you will use another arrangement than strap chainplates but the comments above stand for the record.

The 2nd photo below is of the cap shrouds and their chainplates. The deck cover plate self tapped in to the deck is not attached to the chainplate - it with suitable adhesive/sealant provides the weather / moisture barrier to the deck cut-out and the ply under the deck and is a well used system, usually works well and is easily refurbished if needed. This ply bulkhead is not epoxied to the underside of the sidedeck or the inner topsides - see prior photo and below it is screwed to grp members and presumably has suitable adhesive as well - but it is essentially a full cross section bulkhead (except for the cut-out to the fwd berth) not two partial bulkheads like you will fit.




Microbe
WA, 166 posts
14 Oct 2020 10:33AM
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Thanks once again for the information and assistance r13.

The bulkhead and strap arrangement on the C22 with the modifications you suggest would be very strong, and would have less moving parts than my proposed solution. The disadvantage is that I wouldn't be able to machine and polish the straps in my limited workshop (and with my limited metal working skills). The cost of getting a professional to do it may also exceed my limited budget - although might not be too much more expensive than a the saddles and turnbuckles I was considering.

I'll have a think about how to proceed and post updates as I do the work.

In terms of the deck repair - I'm not sure there is any damage to the core - there is no sponginess/flex in that area and no detected hollow sounds while knocking on it. My plan at the moment is to chip off the cracked gel coat, sand back to expose clean glass then apply a layer of 400gsm cloth in epoxy and a layer of epoxy + powder, paint over with 2 pack poly and then cover with kiwi grip in non-skid areas. I'll do some core samples around the existing drilled holes and confirm that the core is OK before proceeding down this track.

Cheers!

Zzzzzz
513 posts
14 Oct 2020 2:15PM
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Microbe said..
Thanks,

I was considering something like this - sort of a combination of what you're suggesting and what the other SS22 owner did.

I'll glass a ply semi bulkhead under the deck and run a stainless strap along either side. Chainplates will be saddles on either side of the deck on the same bolts. Then I'll run a turnbuckle from the saddle to the strap. I could also run a strap down the front of the ply and bolt it to the same point on the hull as the existing one for additional strength.

I'll put a stainless strap on either side of the ply and then could have two turnbuckles - one attached to the lowers and one to the caps.




Select to expand quote
Microbe said..
Thanks,

I was considering something like this - sort of a combination of what you're suggesting and what the other SS22 owner did.

I'll glass a ply semi bulkhead under the deck and run a stainless strap along either side. Chainplates will be saddles on either side of the deck on the same bolts. Then I'll run a turnbuckle from the saddle to the strap. I could also run a strap down the front of the ply and bolt it to the same point on the hull as the existing one for additional strength.

I'll put a stainless strap on either side of the ply and then could have two turnbuckles - one attached to the lowers and one to the caps.



Finding this thread very interesting, I am no expert on rigging but that very detailed drawing brings to my mind quite a complex amount of fittings and only one of them has to let go to lose the lot , is there any such thing as a tested saddle? They look to take the most load.

Microbe
WA, 166 posts
14 Oct 2020 4:43PM
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Zzzzzz said..




Finding this thread very interesting, I am no expert on rigging but that very detailed drawing brings to my mind quite a complex amount of fittings and only one of them has to let go to lose the lot , is there any such thing as a tested saddle? They look to take the most load.



Quite right - I'm not going to find a manufacturer's load rating for the saddles, so would just have to work off the tensile strength of the amount of stainless steel that goes in to them. Other in-field testing has been done - I've seen a few boats rigged with saddles like this. My previous boat (Sonata 6 with a custom fractional rig) had, and still has, this system. Another Spacey 22 owner told me that a similar system that's been in place for 10+ years on his boat has only had one failure - and that was from a poorly manufactured bolt. And my concern would be the bolts, more than the saddles. Regular inspection and replacement would be important.

Although it might not be as bullet proof as r13's suggestion it would be an improvement on the existing system that relies on the strength of a couple of tired looking welds and places all the rigging loads in to the deck.

r13
NSW, 1427 posts
14 Oct 2020 7:52PM
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Thanks Microbe

Yes was concerned with your busy schematic including turnbuckles under the deck..........but didn't want to interfere........

Edcon over here in the east are brilliant suppliers of all steels including stainless and will cut to size. Last time I was there (Revesby Sydney) it was $10 min order.

Maybe Stirling over your way can cut the 6x50 316ss flatbar to the 2 off 300mm long pieces needed? In the 2m length they have 5x30 for $22 plus tax which would surely be fine. Or 6x50 $46+tax.

see here;

www.stirlingsshop.com/500/index.php?route=product/category&path=35_40_286

You would make up the chain plate straps very easily in your workshop. No machining needed. Cobalt 32tpi hacksaw blades and cobalt drill bits would assist, slow speed drilling. Say r5mm radius on all 4 corners of each chain plate strap. Neatly finish off each radius with filing.

Good one Zzzz I thought Ronstan saddles would have been load rated but they are not - this is very surprising and Ronstan must address this.

www.ronstan.com.au/marine5/range.asp?RnID=246

In the lifting tackle industry Rud links are load rated for every angle and application they are certified to be used for...............get them from Bullivants if you are doing any serious lifting and don't want to spoil your day.

www.rud.com.au/product-category/lifting-lashing-solutions/lifting-points/

Looks like you are fully onto the deck repair scheme needed.








Microbe
WA, 166 posts
14 Oct 2020 5:16PM
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r13 - I've sent out for a few quotes from stainless companies over here in Perth to supply 4 chainplates, including rounding the ends and drilling them for me. I'll see what they come back with. I did get a quote from a Qld company for cutting to length and polishing the straps - $134.

So, whilst waiting for the quotes to come in: two other things are on my mind.
1. Where can I get chainplate deck covers for 6x50 chainplates?
2. How do I attach my wobble stoppers to the cap shroud chainplates. My existing system is a piece of flat bar attached to the chainplate with a shackle. The shackle in the system reduces the wobble stopper's effectiveness; essentially it makes a wobbly wobble stopper. Other Spacey 22s seem to have a piece of stainless tube fashioned in to a toggle at the deck end and flattened out at the other (see pics attached). My concern with that system is that it relies on the 1.6mm wall of the tubing.

Any thoughts?





r13
NSW, 1427 posts
14 Oct 2020 9:31PM
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Hello Microbe

Q1 - I don't expect you will get chain plate deck covers for any size chain plate flat bar strap off the shelf sorry. Have to make them up yourself - only 1-2mm thick stainless is needed. Cobalt drill out clearance holes ducks in a row and hand file them out to make the slot. Drill the 4 corner holes for the self tappers.

Q2 - wobble stoppers to cap shroud chain plates - flat bar and shackle making wobble wobble stopper. So we need to be clear here that during the mast raising / lowering process there potentially is wobble (and hence loads needing to be resisted in strength and fatigue) laterally as well as fore and aft.

a Having difficulty answering in the correct order so this might be a tad out of sequence - firstly obviously the saddles in your latest photos of the other SS22 are 90deg differently oriented to yours - so their bolts are fore and aft whereas yours are lateral. Your orientation is far better for the case of the saddles not being loaded exactly in their vertical plane as the load direction will surely shift inboard under the wobble loading of mast raising and lowering. So the caps might load the saddles in the vertical plane under normal use but for the case of the sideways wobble when the mast is being lowered they surely will not be loaded only vertically - there will be an inwards load orientation onto the saddles and for the latest photos that is by far the weakest strength direction of the saddles and a real concern - depending on the load and angle magnitudes obviously. For the diagonals there is an inwards load angle by design and again your direction orientation is far better.

b But for the mast raising / lowering case there would be loads in the fore and aft direction on the saddles during the whole process. So in this case the fore and aft oriented saddled would be preferred.

c The stainless tube with toggle end at deck and flattened out higher up to meet the cap shroud turnbuckle is very unusual, unexpected, and not recommended as you surmise, with the 1.6mm wall of the tube subject to very high bearing stresses from the pin connections at each end. Bearing stresses - compression loads on the hole due to the through bolt or pin - have the highest allowable steady state load magnitude of all stresses but the arrangement is not recommended imho. The fatigue performance of bolt hole bearing stresses is well reduced from steady state load stresses. Note however that this tube arrangement and the turnbuckle and toggle end higher up in effect has rotational freedoms in both planes due to the pins being in 90deg different orientations - but the deck saddle loading for inwards loads is still not advised.

d The 6x50 chain plates with turnbuckles (and their toggles) for caps and diagonals should be far more resilient in strength and fatigue than your original welded arrangement, and any saddle arrangement. Note that for fatigue a repeated cycle load case of less than 1000 is not considered - obviously if a strength load case of less than 1000 cycles occurs, of a magnitude so as to cause yielding in any component, then there is a problem.

e So your flat bar in the caps and the above tube in the caps - why cannot a normal cap shroud with turnbuckle and toggle be fitted to a flat bar chain plate? Have the turnbuckle toggle end pin as low as possible to the deck so that the chain plate flat bar bending moment at the deck junction is not amplified under the mast fore and aft loads when raising / lowering.

Microbe
WA, 166 posts
15 Oct 2020 8:38AM
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Thanks r13.

" why cannot a normal cap shroud with turnbuckle and toggle be fitted to a flat bar chain plate?" - are you suggesting to run the shrouds all the way to the chainplate and do away with any wobble stopper arrangement?

The idea behind the chainplate extender/wobble stopper is to form a solid section of rigging that extends the shroud connection up from the deck level and brings it in line with the pivot point of the mast step. A support wire is run forward from the extender to the deck so that the extender stays vertical as the mast pivots. This is supposed to allow tension to be kept on the caps as the mast pivots down, but various factors in the design mean that there will always be some slack, but not enough to cause damage to the mast step (on an 8m mast, lateral movement of 14cm at the mast head only equates to 1 degree of deflection at the step). It will keep your mast from going over the side when that stink boat or Rottnest ferry roars past when the mast is half way down.

Getting rid of the wobble stopper would result in a simpler, stronger set up for sailing - which would be 99.9% of the boat usage. Introducing a weak link for the sake of the 0.1% case does seem counter intuitive, but when I'm standing on the narrow deck of the boat trying to wrestle an 8m pole in to the mouth of a mast crutch and watching the ferry bearing down on me I appreciate all the help I can get.

r13
NSW, 1427 posts
15 Oct 2020 3:06PM
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Ok got it, good one. Certainly agree you need that wobble stopper function to be maintained for the reasons you outline.

Microbe
WA, 166 posts
15 Oct 2020 1:00PM
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I'm thinking it might be possible to manufacture a connector to sit between the chainplate and the wobble stopper.

What I have in mind is a short piece of 30x30 square section stainless bar with a 10mm wide slot cut in one end with a pin through for attaching to the chainplate, and a slot cut at 90 degrees to that first slot in the other end with a pin through for connection to the stainless strap that currently forms the wobble stopper.

I'm envisioning something like this anchor connector, but out of a single solid piece - no swivel in the body.

Or, I could use a piece of 25mm round bar for the whole length of the wobble stopper. Cut a fork in one end for the chainplate and grind the other end to be flat to take the turnbuckle.

Guess it all depends on what I can achieve with my limited workshop (angle grinder, hacksaw and hand files)

Or, use one of these: www.ronstan.com.au/marine5/product.asp?ProdNo=RF816

r13
NSW, 1427 posts
15 Oct 2020 7:56PM
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Yes good thoughts.

The first option with short 30x30 square bar length to the flat bar length seems too busy sorry to say, is unnecessarily introducing more components and all the edges on those square and flat bars will not do sails or ropes or hands/fingers/arms /legs any good.

The 2nd option with 25mm round bar for the whole length seems a lot more palatable. For the fork end to the chain plate drill a hole 1mm larger diameter than the chain plate thickness and hacksaw into the sides of it so that the stress concentration of the fork end is not excessive. Finish carefully with hand files - rat tail and flat files. For the flat ground end similarly fair the flats into the round bar with suitable radius - finish with suitable 1/2 round files. Your workshop would benefit with a drill press for the hole drilling - and also a suitable drill press vice. Or a mate could have these? Bunnings have both for <$200.

The RF816 looks good but its breaking load of 1000kg (point loaded pins) and 1200kg (uniformly distributed loading of pins) is below a typical 4mm 1x19 316 ss wire which you are maybe using as caps - at around 1340kg. All fittings in the standing rigging must be greater breaking loading than the wire.

Microbe
WA, 166 posts
15 Oct 2020 6:45PM
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Great, thanks for the feedback. I spoke to a fabricator today about getting the parts made up for me, including the full length 25mm round bar. Getting close to a final solution.

I do have a drill press, but could do with a drill press vice. I really should join the local men's shed. They have a fantastic metal shop (and blokes with the skills to use all the tools)

r13
NSW, 1427 posts
15 Oct 2020 11:20PM
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Ok good.

If you have a drill press a good strong clamp can suffice to hold the part being drilled - albeit a round bar makes it more critical for securing integrity as it can inherently rock / roll. Need to centre punch the hole location really well and start with small drills and work up to the final diameter.

Zzzzzz
513 posts
16 Oct 2020 3:13AM
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I understand the modern way of doing chain plates through the deck into the bulkhead is better for the sheeting angle, but I have never seen one that doesn't leak a real pain never ending And of course most get bolted to plywood bulkheads so eventually you end up with rot and structural integrity.
As a cruiser I have always liked the simplicity of straps down the side of the hull , and if I am right the extra strength of the rigging from the wider angle .

BlueMoon
865 posts
16 Oct 2020 3:44AM
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Zzzzzz said..
I understand the modern way of doing chain plates through the deck into the bulkhead is better for the sheeting angle, but I have never seen one that doesn't leak a real pain never ending And of course most get bolted to plywood bulkheads so eventually you end up with rot and structural integrity.
As a cruiser I have always liked the simplicity of straps down the side of the hull , and if I am right the extra strength of the rigging from the wider angle .


And the important benefit of having clear side decks to walk along

Microbe
WA, 166 posts
16 Oct 2020 8:53AM
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Select to expand quote
Zzzzzz said..
I understand the modern way of doing chain plates through the deck into the bulkhead is better for the sheeting angle, but I have never seen one that doesn't leak a real pain never ending And of course most get bolted to plywood bulkheads so eventually you end up with rot and structural integrity.
As a cruiser I have always liked the simplicity of straps down the side of the hull , and if I am right the extra strength of the rigging from the wider angle .


Yes, I worry that cutting big holes in my deck for the chainplates will increase the chance of leaks - but I have bolts passing through the decks for the existing deck mounted chainplates and they are leaking, so... swings and roundabouts.

I did consider taking the caps out to the side of the hull, but wasn't sure I could do that without getting longer spreaders.

r13
NSW, 1427 posts
16 Oct 2020 1:35PM
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The purpose of the deck cover plates with 4 self tappers (see photo above) is, in conjunction with suitable sealant and properly done, to seal the deck chain plate slot from any and all water ingress. I have had many yachts with this arrangement which do not leak.

Without getting into semantics or being pedantic, a wider chain plate base won't increase the strength of the rigging, it will reduce the loads in the rigging.

Yes longer spreaders would be needed if widening the chain plate location.

Microbe
WA, 166 posts
16 Oct 2020 4:18PM
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Some good news from the metal worker! Just got the quote for supplying the steel and machining to the dimensions we've been discussing.

The good news is that I could soon have a well equipped metal workshop, because it would be cheaper for me to buy all the required machinery and do the job myself!

Zzzzzz
513 posts
16 Oct 2020 4:30PM
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Fantastic news I have some work for you

Jolene
WA, 1554 posts
17 Oct 2020 6:52AM
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Tube type chain plate extenders with a fabricated fork to receive the chain plate.





Microbe
WA, 166 posts
17 Oct 2020 3:11PM
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A big day today, and the first of many to come. Today I dropped the mast, removed the furling gear, took off all the standing rigging and secured the mast to the crutches that will have to hold it for a month whilst I do the deck repairs.

Here's a shot showing the wobble stopper in action.

The seagulls seem to appreciate the nice long roost I set up for them.


Lots of wire. Pockets full of clevis pins. Hope I remember how it all goes back together.



r13
NSW, 1427 posts
17 Oct 2020 7:12PM
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Great work, and sure it will go well.

Microbe
WA, 166 posts
17 Oct 2020 5:45PM
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Whilst out in the moorings I took the opportunity to do a survey of the chainplates and wobble stoppers on nearby boats.

This is from a Spacesailer 27. Nice strong through deck chainplate. Wobble stopper is tube with welded lugs either end.

This is the chainplates on a magnum 8.5. Solid piece of steel, but welded to a deck connection plate. Nice long weld, but I wonder if the lowers pulling forward like that is good for it.

This is the wobble stopper from a 30ftr. Tube with a welded u at the bottom (had a welded tongue at the top). Not sure i like this one.


Microbe
WA, 166 posts
25 Oct 2020 2:26PM
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Well, I'm glad I decided to heed the advice from this forum and replace my rigging and chainplates. Today I removed the old fittings and as I was undoing one of the bolts the head snapped off. This is obviously where the rust staining was coming from.


Now that the tension of the rigging has gone the deck has been allowed to settle as can be seen in the extra slack in the tension strap.


I dropped my shrouds to the rigger to get replaced and he pointed out several things that could have made the whole rig collapse. He also confirmed that the turnbuckles were about 30 years old.



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"Deck repair advice" started by Microbe