Had a violent wind direction change off Coffs Harbour this week, I was cruising along under main with 13 knots behind, all good! There was some lightening pre close, that was my greatest fear, but then, out of no where I was hit with a Westerly, I saw 36 knots. A crash jibe ensued. The first thing I noticed was the main halyard lost tension, so I reefed down to first reef. But after all the commotion I was horrified to discover the boom section had bent, right where the main sheet blocks attach. So there was some force involved as the boom is pretty stout, a Selden rounded square section 1171mm deep x 94mm wide. The dyneema 8mm covered halyard broke the outer. I called the agents expecting the replacement B171 section to be around $1000~1500. Alas no, they tell me you need to buy the complete long boom and cut it down to your chosen length, ok how much? Lucky I was sitting down, $4900 approx.

Okay so if anyone is familiar with Selden B171 alloy extrusion and maybe knows where I can get some, to simply rebuild my boom with the existing components. I'm all ears!

My extrusion measures 4360mm OA

Cheers in advance, Richard

I had a crash gybe at Lord Howe. Snapped the boom off at the goose neck. That was exciting in very big seas.

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MorningBird said..
I had a crash gybe at Lord Howe. Snapped the boom off at the goose neck. That was exciting in very big seas.

Thanks MB at least my boom is still in one piece. It may even be okay in light conditions to run the main. Otherwise I need to use the "diesel main" for the rest of the trip to home port.

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Stockie said..
Had a violent wind direction change off Coffs Harbour this week, I was cruising along under main with 13 knots behind, all good! There was some lightening pre close, that was my greatest fear, but then, out of no where I was hit with a Westerly, I saw 36 knots. A crash jibe ensued. The first thing I noticed was the main halyard lost tension, so I reefed down to first reef. But after all the commotion I was horrified to discover the boom section had bent, right where the main sheet blocks attach. So there was some force involved as the boom is pretty stout, a Selden rounded square section 1171mm deep x 94mm wide. The dyneema 8mm covered halyard broke the outer. I called the agents expecting the replacement B171 section to be around $1000~1500. Alas no, they tell me you need to buy the complete long boom and cut it down to your chosen length, ok how much? Lucky I was sitting down, $4900 approx.

Okay so if anyone is familiar with Selden B171 alloy extrusion and maybe knows where I can get some, to simply rebuild my boom with the existing components. I'm all ears!

My extrusion measures 4360mm OA

Cheers in advance, Richard

Wow Stockie, that must have been a shock! I reckon my Selden boom is very similar to yours and it's scary trying to imagine the force needed to bend the thing. And ouch, $4.9k for a boom section, the shock just keeps on giving doesn't it! I'll ask around down here for you to see If anyone has one, so it's 4360 OA is that without the cast end sections that plug into it, so just the length of the actual extrusion? Is it repairable by welding in a piece where the bend is If you found a shorter section?

Wonder what the price of a full Southern Spars carbon boom would be as a comparison?

Couple of booms here and they might be a good telephone call: www.sailexchange.com.au/collections/epirb-19?p=2

Hey,
Unlucky on the break.
Any chance of some pics?
Might be able to point you in the right direction to save you some $$

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2bish said..
Couple of booms here and they might be a good telephone call: www.sailexchange.com.au/collections/epirb-19?p=2

Thank you 2bish I'll follow up Monday. That dimension was just the extrusion length. I have been thinking of all sorts of ways to just insert a new section between my perfectly serviceable end castings. I have even thought of using sail track extrusion for the single line reef cars to run in. But can't find anyone on line doing 200x100mm extrusion.
Thanks for you efforts, I let you know how it pans out?

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rumblefish said..
Hey,
Unlucky on the break.
Any chance of some pics?
Might be able to point you in the right direction to save you some $$

How bent is it?
Doesn't look too bad structurally from that pic.

Maybe straighten and put external sleeves on?
The reason the new one is so expensive is the single line reefing and Selden in Oz only want to sell the whole thing!!

As per rumblefish, assuming that the whole boom is not bent but just the local wall damage has occurred, it must be possible to straighten out the local wall damage which appears to be a classic compression buckling deformation, and rivet and epoxy glue an external doubler on? Ok it won't be a pristine "as new" finish but if done correctly will certainly be strong enough to get you back to home port? Use 6061-T6 alum plate of the same thickness as the wall thickness of your boom, and 3/16 monel rivets. Looks like you will need 3 strips based on that photo which seems to show 3 different panels down the height of the section. Suggest each strip is about 600mm long - taper them at each end say 3:1 taper and radius the end so as to not make a hot spot stress concentration at their ends. To straighten the local wall damage drill holes where the rivets close to the damage will go, and use some sort of blind bolt system to insert and then heave on it from the outside to bring the wall back out to where it was - this will probably be the hardest part of the job. I sleeved a quarter tonner mast 12 years ago with this method when refurbishing it and on taking the spreaders off there was a hole about 50mm diameter in the mast each side under the ss spreader band where the galvanic corrosion barrier system between the spreader band and the mast had broken down - the alum of the mast just corroded away......not sure how the mast still stayed up in the sailing prior to the slipping which included 25kts up the harbour and back in a top noreaster - it worked perfectly but needed a lot of epoxy glue to ensure everything was flushed with epoxy - the mast and external doubler, the holes and rivets - needed excellent surface preparation to get everything back to bare aluminium and acetone or IPA cleaning then whole new polyurethane repaint of the complete mast including etch priming the bare alum - your boom seems to be anodised so just IPA cleaning should suffice. See here for good discussion on alum grades....forums.sailinganarchy.com/index.php?/topic/162604-aluminum-used-in-spars-changed-in-20-years/

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rumblefish said..
How bent is it?
Doesn't look too bad structurally from that pic.

Maybe straighten and put external sleeves on?
The reason the new one is so expensive is the single line reefing and Selden in Oz only want to sell the whole thing!!

Yes I was wondering if I tell them it is not SLR, and get a boom without this feature, and just transfer over my stuff, I assume the sections are the same with the internal tracks to suit the reef cars.
im not going to try and fix it enroute, if I get beam winds I can make great progress under Gennaker only, or if the breeze is up, yusttge headsail.
The picture sides shows the deformation, the other side is no crease.

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Stockie said..

MorningBird said..
I had a crash gybe at Lord Howe. Snapped the boom off at the goose neck. That was exciting in very big seas.

Thanks MB at least my boom is still in one piece. It may even be okay in light conditions to run the main. Otherwise I need to use the "diesel main" for the rest of the trip to home port.

We got to LHI and removed the boom. Came home with the trisail.
Joe Walsh repaired the boom for $300.
I suppose MB is a simple boat so repairs are a bit more straightforward.

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Stockie said..

That photo shows that the load point can no longer be depended upon.
If you have to have Selden,you have to pay the price.
I believe you could source a strong enough section locally with end fittings for way less money.

Hi Stokie
At first I thought this is a Selden fault and searched for broken or bent Selden boom.
Nothing came up , so seems that you have a pretty unique situation.
You have five choices. These are listed in diminishing replace costs.
Replace as per original.
Replace with new complete boom rig (as Cisco has suggested)
Have a new custom boom made up in carbon fibre composite.
Replace with secondhand complete boom rig
Repair.


If you do replace with the original Selden setup, you will live in fear of a re-occurrence.

I am sure you are onto this already.
A repair on a mast is usually as strong or even stronger that original, as the spar is in compression.
However this is not the case with the boom. Any sleeve or 2 half profile sleeves will need to be quite long (up to a metre = 500 cm each side of the weak point.
Probably not possible to make an internal sleeve ( as this would be complicated by internal lines and would require the boom to be sawn in half.)
So, I would not recommend repairing.

I hope you can source a complete secondhand boom rig. That would seem to be the most painless route.

All the best

gary

Hey Stockie, do you have insurance policy?
If so, can you claim a new Seldon including the labour to have it fitted?

just a thought

Hi Stockie

How did the damage occur

Did the boom go across on to the shrouds or was it just that the sudden stop at the end of the gybe that caused it to bend

Regards Don

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Stockie said..
Had a violent wind direction change off Coffs Harbour this week, I was cruising along under main with 13 knots behind, all good! There was some lightening pre close, that was my greatest fear, but then, out of no where I was hit with a Westerly, I saw 36 knots. A crash jibe ensued. The first thing I noticed was the main halyard lost tension, so I reefed down to first reef. But after all the commotion I was horrified to discover the boom section had bent, right where the main sheet blocks attach. So there was some force involved as the boom is pretty stout, a Selden rounded square section 1171mm deep x 94mm wide. The dyneema 8mm covered halyard broke the outer. I called the agents expecting the replacement B171 section to be around $1000~1500. Alas no, they tell me you need to buy the complete long boom and cut it down to your chosen length, ok how much? Lucky I was sitting down, $4900 approx.

Okay so if anyone is familiar with Selden B171 alloy extrusion and maybe knows where I can get some, to simply rebuild my boom with the existing components. I'm all ears!

My extrusion measures 4360mm OA

Cheers in advance, Richard

Richard, I have a complete boom including all reefing and out haul lines which came off our Hanse 57. It has two reef lines which are single line reefing. The boom would easily be shortened to suit your boat and would be a lot stronger than your original boom. The boom is in as new condition as it was only on the boat for three months while waiting for our furling boom. PM me if you are interested.
regards
John

Hi all

On old boats the booms seem to be mainly round and on the newer ones they seem to be rectangular

Like for like is there any strength advantage of either section

Regards Don

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Donk107 said..
Hi all

On old boats the booms seem to be mainly round and on the newer ones they seem to be rectangular

Like for like is there any strength advantage of either section

Regards Don

Round will always be stronger than rectangular. When a cross brace is added stronger again. I changed the boom on my old quarter tonner to a section of a Hobie 16 mast I picked up from a scrap yard. More oval than round but a very strong section.

Need to calculate the moment of inertia (2nd moment of area) of the exact cross sectional geometry to see which is stiffer. Given equal wall thickness and material (ie 6061 T6 alum), if you are comparing a rectangular hollow section boom of same depth as the round section tube, but (say) 2/3 the width of the round section tube, then the vertical stiffness of the rect will be greater than the round, but the lateral stiffness will probably be less. So need to do the calcs. All mast / boom suppliers will give you the inertia calcs. For round tube and square hollow section of the same depth and width, and same wall thickness and material, the square hollow section will be stiffer.
Seems like no answer yet on whether the boom hit the shroud - by the look of the photos imho it did not - there would have been heaps more damage if it did, including to the shroud, chainplate, mast etc etc............so just the compression buckling at the block from the wild swing as halted by the figure of 8 knot in the mainsheet...........

When mine let go, it was the same spot, that was where the mainsheet attaches. Hard way to learn to sheet hard on the mainsheet before gybing :)
the replacement boom was just shy of $5k for a 5mtr x 200mm x 150mm span.

Sorry for late reply, it was a chars unexpected gybe, NE to W in a nano second. I never let my boom go anywhere near shrouds if I can help it, to hard on the main, with swept back spreaders for starters. And I sheet fully in for intended gybes. I learnt from sailboard days, duck gybes are best, less stress etc.
I can go insurance, but I will enquire a about jodes boom too.

PS I have sailed back to Pittwater on this boom, so it is hanging in, should get me to Port Hacking tomorrow. Great conversation starter, haha!
Richard

At least yours was uncontrolled Richard, that's a much better excuse than my badly executed gybe. I did exactly what some poor sod did in the Volvo (which tore their mast track off the mast). We were surfing down a wave and timed the gybe for the trough to take advantage of the flatter water and less pressure from the speed and subsequent lull. First mistake was I felt the hint of a strong gust right in the middle of the trough and still gybed. And the gust came in.
The second problem was I didn't notice the mainsheet was still eased.
We were sheeting on as a general rule, but we got lazy and as a result, broken bits.
Expensive lesson that one.

Hi all

Not knocking either boat but accidental or intentional gybes that go wrong seem to be part of sailing and I would have thought that the boom should be designed to be strong enough to not fail when one happens

Regards Don

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Donk107 said..
Hi all

Not knocking either boat but accidental or intentional gybes that go wrong seem to be part of sailing and I would have thought that the boom should be designed to be strong enough to not fail when one happens

Regards Don

I agree Don. It was no windier than what Richard described, 30-35 knots, so not what you'd class as survival mode.
Looking at the damage, you could see a couple of different ways you could engineer the end plate/ boom section to be much more robust.
Which the new boom does. Zero chance of folding this one.
Touch wood.

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shaggybaxter said..

Donk107 said..
Hi all

Not knocking either boat but accidental or intentional gybes that go wrong seem to be part of sailing and I would have thought that the boom should be designed to be strong enough to not fail when one happens

Regards Don

I agree Don. It was no windier than what Richard described, 30-35 knots, so not what you'd class as survival mode.
Looking at the damage, you could see a couple of different ways you could engineer the end plate/ boom section to be much more robust.
Which the new boom does. Zero chance of folding this one.
Touch wood.

Hi Shaggy

When I look at some of the small size shackles and fixtures on boats they seem small for the loads that I imagine that they deal with but I suppose that the designers and engineers have done the maths or is everything just big enough with out too much in reserve

If I was doing it at home in a lot of cases I would go bigger than what the manufacturers use but perhaps all I would be doing is adding unnecessary weight

Regards Don

Looking at the boom failure, it seems that the connection of the main sheet blocks had a lot to do with the failure. Is there a lot of weight in the end of the boom? It was the inertia of the boom aft of the mainsheet blocks, plus wind forces of the sail, which probably caused the boom to fail in bending, however that block connection must have done a lot of added distortion.
If it were my boat, I would move the main sheet block connection aft, and use a more distributed load attachment design. Then I would plate the side of the boom where it buckled, with taper, etc, as described previously. Will not be pretty, but will probably do the job. Umm, and maybe a boom brake....

This is my boom 3/16 section with mainsheet aft Everything bolted on

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Yara said..
Looking at the boom failure, it seems that the connection of the main sheet blocks had a lot to do with the failure. Is there a lot of weight in the end of the boom? It was the inertia of the boom aft of the mainsheet blocks, plus wind forces of the sail, which probably caused the boom to fail in bending, however that block connection must have done a lot of added distortion.
If it were my boat, I would move the main sheet block connection aft, and use a more distributed load attachment design. Then I would plate the side of the boom where it buckled, with taper, etc, as described previously. Will not be pretty, but will probably do the job. Umm, and maybe a boom brake....

I have the same boom but the load is spread out over 3 attachment points - gives me the extra purchase I need as well.

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Lazzz said..

Yara said..
Looking at the boom failure, it seems that the connection of the main sheet blocks had a lot to do with the failure. Is there a lot of weight in the end of the boom? It was the inertia of the boom aft of the mainsheet blocks, plus wind forces of the sail, which probably caused the boom to fail in bending, however that block connection must have done a lot of added distortion.
If it were my boat, I would move the main sheet block connection aft, and use a more distributed load attachment design. Then I would plate the side of the boom where it buckled, with taper, etc, as described previously. Will not be pretty, but will probably do the job. Umm, and maybe a boom brake....

I have the same boom but the load is spread out over 3 attachment points - gives me the extra purchase I need as well.

Hi Lazzz

looking at a photo of Stockies boat the main sheet set up is the same as yours

Regards Don

They all seem to need a $13 climbers figure 8 and a lump of old rope and rig up a boom brake.