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Through Bolting Boom Block Eyestrap

J22sailor

New Member
I recently had the unforunate experience of having the forward eyestrap on my boom and the bullet block attached to the same get pulled out of my boom due to heavy wind.

I am going to through bolt the eyestrap to avoid this happening again and wondered if I can simply drill out the top of the boom to have the bolts go straight through the entire boom with the nuts being installed on the bottom eyestrap side.

I know the official "laser throughbolt kit" has you remove the gooseneck plug and then install the bolts from inside the boom....but drilling through the top of the boom seemed an easier venture to me. Iis there a reason to not simply drill through the boom? Thanks in advance for any insight.
 

xflyer95

New Member
The thru bolting subject has come up on sim topics, mainly the reinforcing sleeve, and as I recall there were many who feel that the boom will be weakened by doing so. I assume you had stainless rivets and not aluminum.....best of luck Eric
 

Bungo Pete

Member
The method you describe will entail drilling a hole large enough to get the head of the machine screw through the tube wall of the boom. Given the thickness of the aluminum used to manufacture the boom, this may be OK. If it were me however, I WOULD NOT DO IT. The cost of a gooseneck cap is a small price to pay for not compromising the strength of your boom.

If you run a search, you will find some pics I posted about 2 years ago showing how I through-bolted all my eyestraps and the steps I took to keep corrosion to a minimum and strengthen the joint between the eyestrap and the boom. It entails using fender washers, nylon washers and a LOT of Lanocoat. You also do not need to purchase the kits from APS.

Hope this helps.
 

J22sailor

New Member
thanks for the input...

Pete, the method I was considering was to install a long bolt through the entire boom with the bolt head remaining on the outside and the top of the boom. In reading older posts, it seems like the general census is that a bolt extending through the entire boom would weaken the boom. But I wanted to hear some thoughts and prior experience.
 

49208

Tentmaker
My memory is a bit fuzzy as it was the mid 70's, but seem to recall a few friends who took the lazy way out and thru bolted thru the whole section. Both booms eventually broke right at the forward bolt, starting at the top.

I would also recommend that instead of removing the gooseneck plug, you remove the aft end plug, that way you can also thru bolt the aft block and 1/2 of the outhaul fairlead at the same time.
 

AlanD

Former ISAF Laser Measurer
The difference between the 70's and now is the longer sleeve which now extends beyond the front block on the boom. Prior to the longer sleeve being introduced booms regularly broke in the vicinity of this block, but since it's introduction booms very rarely break.
 

49208

Tentmaker
The difference between the 70's and now is the longer sleeve which now extends beyond the front block on the boom. Prior to the longer sleeve being introduced booms regularly broke in the vicinity of this block, but since it's introduction booms very rarely break.
So, are you suggesting you would not have a problem thru bolting completely thru the whole section as the orignal poster wants to do, sleeve or no sleeve ?

IMHO, two less holes in any spar is always a good thing, and you run the risk of over-tightening the bolt and collapsing the section
 

AlanD

Former ISAF Laser Measurer
So, are you suggesting you would not have a problem thru bolting completely thru the whole section as the orignal poster wants to do, sleeve or no sleeve ?
Correct but with emphasis on "should be".

IMHO, two less holes in any spar is always a good thing, and you run the risk of over-tightening the bolt and collapsing the section
This is also my belief.

In my opinion the OP should retire his existing top section and convert it into a new boom, whilst purchasing a new top section. Forget the through bolting, but use monel rivets throughout with a corrosion inhibitor on all their spars. If rivets are pulling out, it's not due to ductile overload, it's because of corrosion and if the boom is in this shape, the top section will be worse.
 

Bungo Pete

Member
If only the builders would use the inhibitor and monel from the start.....
I hat to burst your bubble regarding this issue, but the use of monel will really not make a difference from a corrosion standpoint - it will still happen. The only advantage of using monel rivets would be that they are softer and thus easier to use due to the higher nickel content. You are correct in that corrosion inhibitors should be used when the boom is first assembled at the factory.

During my rebuild, I used SS screws, fender washers (which I bent to replicate the curvature of the ID of the boom) and nylon washers which you can buy at the hardware store for a couple of cents. I figured that the latter would act as an insulator between the aluminum and the stainless. Naturally, I put as much lanocoat as possible in the interface.
 

Camoplasm

New Member
The method you describe will entail drilling a hole large enough to get the head of the machine screw through the tube wall of the boom. Given the thickness of the aluminum used to manufacture the boom, this may be OK. If it were me however, I WOULD NOT DO IT. The cost of a gooseneck cap is a small price to pay for not compromising the strength of your boom.

If you run a search, you will find some pics I posted about 2 years ago showing how I through-bolted all my eyestraps and the steps I took to keep corrosion to a minimum and strengthen the joint between the eyestrap and the boom. It entails using fender washers, nylon washers and a LOT of Lanocoat. You also do not need to purchase the kits from APS.

Hope this helps.
This is a helpful reply, Bungo Pete. I've considered ordering an APS through-bolting kit, since our club fleet of (~8) Lasers are ocean-going vessels, and corrosion over the years has widened the eyestrap holes for both boom blocks; repeat riveting doesn't last long anymore. I'm curious whether you have any experience with upsizing the rivets (if this is even possible), using stainless steels perhaps, before proceeding to through-bolting?

At any rate, if you can link me to your previous protocol for a quality through-bolting process, that would be great. (Has it held up so far?)

Thanks,
Cameron
 

LaLi

Well-Known Member
Cameron... in case you haven't noticed: 1) this thread is more than eleven years old, 2) Bungo Pete hasn't been here for more than a year, and 3) APS went out of business a year and a half ago :(

About the boom: always use stainless rivets for the sheet block eyestraps, as large as the strap holes allow, and use whatever anti-corrosion stuff that is available in your part of the world. If the holes in the section have grown too big, then just trash it. It's time for a new boom, or if you want to spend the time and effort, you can (as Alan suggested a long time ago) buy new topmasts and make "new" booms out of the old ones.

West Coast Sailing should be able to help you more (although they seem to be out of booms right now).

_
 

Camoplasm

New Member
Hi Lali,

Thanks for the heads-up, and also for the advice. I feel torn about stainless-steel rivets--way sturdier than aluminium obviously, but hard as heck to drill out if they're sized wrong or loosen.... I've never through-bolted a boom before, but it sounds like you're not in favour of that approach. Is that fair? Why so?

Finally, I may be in the same part of the world as you if you're recommending West Coast Sailing. For that reason, I'd like to ask you--any particular anti-corrosion products that you favour in particular? Do you apply them just when changing out metal components like boom eyestraps, or do you use them elsewhere, and for general upkeep? We're a largely volunteer-maintained club, so there's commitment without always having extensive experience with the nitty-gritty of large fleet maintenance.

Thanks much,
Cameron
 

LaLi

Well-Known Member
Actually I am ten time zones ahead of you... and more than ten degrees farther north :D But more importantly, my home waters have the salinity of not more than one-sixth of ocean water, so corrosion is not a big deal here. I don't know from experience if "general upkeep" should include frequent application of anticorrosion materials in your environment. You have to ask the locals!

I wouldn't bolt anything to spars. Bolts are great in that you can undo them quickly, but if the nut (or the head) is unreachable, it kind of misses the point. It's actually much easier to destroy a rivet if needed :confused: If you think stainless means too much trouble, you can go for monel rivets as a compromise. I believe the rigger that I usually work with uses them almost exclusively.

_
 

Riv

Member
For Camoplasm

"We're a largely volunteer-maintained club, so there's commitment without always having extensive experience with the nitty-gritty of large fleet maintenance"

Same here, small club on salty estuary water in the UK. I am the fleet maintenance person.

Corrosion is the number 1 maintenance problem.
We use Duralac. Yellow paint. Cover each part's mating surfaces. Allow to dry and reattach. It is soluble in xylene. Use it for clean up. Wear gloves. Down side is that it is yellow so it's very obvious if you use it. I carry black and silver spray and flash it over if I think it will look bad.

Laser and club fleet philosophy:
1) Reduce risk to reputational damage. We know that for us Laser/Pico/Topper spars will last about 10yrs before corrosion scraps them. We have a budget and rolling replacement plan to avoid breakages on the water/injuries/insurance claims.

2) We run a closed system. We make all Lasers for example as identical as possible, use shackles tightened with pliers to stop members changing the boat's rigging. This happens on Lasers particularly. We hope to be phasing Lasers out and replacing with RS Zests over the next few years as they are difficult to modify and are a closed system straight from the factory.

3) It's the bits around boats that matter almost as much as the boats. We allocate money for trolley replacement and covers. We have just brought a petrol pressure washer to speed up preseason cleaning.

4) Most of day to day organisation has moved to a WhatsApp group. About a third of adult members are on it and we find it vital for quick response to maintenance issues.

Finally, boom eye problem. We only race within the club. Lasers have little re-sale value. So I would move the boom eye forwards and drill new holes between the worn out ones. Re-rivet with SS and paint rivets as well as strap and mating surfaces with Duralac.

Put aluminium rivets in the old holes to fill them. If the hole is to big you can wrap the rivet in aluminium foil. It's there just to keep the water out.
 

LaLi

Well-Known Member
Good points from Riv, as usual :) The name "Duralac" and the yellow colour do ring a bell now that you mention it.

I would move the boom eye forwards and drill new holes between the worn out ones.
This certainly is an option. You can even stay class-legal as the tolerances allow for exactly this. The min/max measurements from the aft edge of the aft plug to the middle of the eyestrap are 59 to 83 mm for the aft sheet block, and 1641 to 1665 mm for the forward one.

The question is, do you want extra holes in the middle of the boom, close to the point of maximum tension? Given the choice, I'd nevertheless prefer several holes in a row rather than at the same cross-section as the original poster suggested a while ago...

Cameron, how old are your boats?

_
 

kellymac24

New Member
I wouldn't through bolt, putting more holes in the boom is just going to add more weak spots and more spots to corrode faster. I've done a tone of these repairs for myself and the booms at my club. Use the same holes but use a machine screw, nut, teflon washer, and washer.
1. Pop off whatever end cap is closest
2. If its the aft end block its easy and you can probably get the screws through by hand, if its the one closer to the mast you'll have to tie some fishing line to it and jimmy it through (this can be a PAIN)
3.Set up the screws washer first(this will help distribute the load) then the teflon washer to keep the stainless and aluminum away from each other to slow the corrosion process.
4. Put the screws through the inside of the boom and put the nuts on the outside
5. Grind off the excess and you're good to go
 

kimbodious

New Member
I just bolted the gooseneck onto the lower (radial) mast base. I threaded brickies twine in from the outside of the hole. I used a hot glue gun to stick the twine to the end of the machine screw. It was then easy to draw the twine and the machine screw back out the hole.
 
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