drilling the spar for steaming/deck light

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drilling the spar for steaming/deck light

Postby mike cunningham » Sat Nov 05, 2016 2:26 pm

I am asking this question after having done the job but, since I have to do it again, I thought I would reach out.

Background:

During prep for the Transpac I had the mast out to accomplish a few things

Replace the VHF antenna - worked great with HUGE caveat described below.
Replace the RG 58 VHF cable with low loss LMR-400 - worked great
replace masthead wire insulation - retained original Belkin multi-conductor power cable but replaced old gnarly insulation with new pipe insulation foam - worked great
Moved wind transducer from stern mounted pole to masthead - worked great aand vastly improved accuracy
install LED tricolor/flasher/anchor light including wiring - worked great with caveat deccribed below
replace masthead steaming light with mid mast steaming/decklight combo from Forespar - worked great - for a few days


Mistakes I made - a bunch

used a boatyard which focused mostly on power boats. Did a lot of cosmetic damage to the mast and interior. Like an idiot I was not on site for unstep and step. Never again. Headed to Berkeley Marine Center this time. They have lots of experience with SVs

Misaligned the tricolor by about 10 degrees

Placed the new steaming/deck light about four feet above the jib halyard exit and did not install a guard. As a result found myself in mid Pacific with a fouled main halyard which took three hours to clear. This happened twice. This and other stuff like it cost me 36 hours more or less, a huge hit to my performance.

Purchased and installed a Tram VHF whip antenna which has a serious design defect. The whip can and did twist itself off the base of the mount leading to loss of the antenna which, in turn caused loss of AIS and VHF. This happened once on the way out and once on the way back. Took that long to figure out what was going on. The first time I thought it was a fluke, second time I realized something was wrong. I simulated mast top movement by hand and was able to walk the antenna right off the base. Wow!!

failed to reseal the mast deck penetration properly and had terrible leakage over to Hawaii and back.

failed to inspect mast base movement and experienced the infamous "mast bang" for 5000 miles.

Did a poor job of wiring the new steaming/deck light. Wiring has failed (as I half expected it would when I installed it).

My only defense is I was way late with my prep. and I was going to race come hell or high water. I had a pre race inspection which was scheduled as soon as I left the yard so I just had to get out of there. Obviously I got in to much rush.

Now, finally to my question.

In all of the above, the only mast drilling I had to do was for the install of the steaming/deck light. I drilled four small holes for the light flange fasteners and a 1/4 inch hole for the wiring. I am going to have to expand the wiring hole to accommodate a newly purchased 3 conductor cable. Probably something on the order of 3/8 inch. This time instead of trying to splice into the main cable to the masthead, I am installing a dedicated cable for this light.

Is a 3/8 inch hole going to be a problem?? Heck, I already have a 1/4 inch hole up there and survived 40-45 KT winds so I assume the answer is yes but what do you all think?

Mike
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Re: drilling the spar for steaming/deck light

Postby bad » Sun Nov 06, 2016 12:59 pm

I'm pretty sure that high up and that size hole will not matter, but you might find out that if you strip the sheath the individual wires fit through the 1/4" hole. Are you running 16 gauge?

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Re: drilling the spar for steaming/deck light

Postby gamayun » Sun Nov 06, 2016 1:59 pm

Nice summary, Mike! This reminds me that I need to write up my masthead work one of these days. I have also recently noticed that in changing the lazyjacks from coated wire to rope that the halyard is sometimes hanging up on those tangs on the mast. I need to work on that, too.

As to making holes in the mast, I have been extremely reluctant to do that or even enlarge the ones that I have though I did that at the mast base where the wires come out because that was too small and constricting. You might want to give a call to Panda Love in Alameda. I hired him to do the CF repair when I installed the new (and separate) jib and spinnaker sheave boxes. Perhaps you already know this, but it was all new to me, so what I took away from that experience is that you don't want to have any sharp edges to minimize the stress points, and you want to make sure that the fittings are well bedded with the CF since there's high galvanic corrosion with aluminum and stainless.
Kynntana, Freedom 38
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Re: drilling the spar for steaming/deck light

Postby markh77 » Sun Nov 06, 2016 9:32 pm

I agree that any holes must be chamfered to eliminated stress, When building an airplane all holes are deburred because any stress lines can be very bad. Same for a mast. For the exterior of the mast, it is pretty easy. For the inside of the mast there is a deburring tool that allows you to round the inside. I have one but I am not sure it would be sharp enough for carbon fiber. I doubt that the small increase in the size of the hole is any where as important as smoothing the transition.
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Re: drilling the spar for steaming/deck light

Postby mike cunningham » Mon Nov 07, 2016 11:45 am

I was aware of the chamfer/deburring but did not consider inside edge of holes. I'll talk to you about that when I see you Mark.

Re bedding screws. How do you do that? I have stainless screws directly into the CF. I know it's not the best but how do you implement a barrier.
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Re: drilling the spar for steaming/deck light

Postby Camino » Thu Dec 08, 2016 10:14 pm

Great job on the Transpac! Watched via SSS. Sorry to chime in late here - I have a F35 (P) in SF Bay - I'm going to be adding a Mack Pack and am asking advice on adding 3 canvas snaps to the mast (3 port/3 stbd) at 3' above gooseneck or thereabouts - is this doable with the CF mast? Snaps for mack pack are two screws each (10-24) Suggestions?

Thanks and Regards

Cheers

Tom
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Re: drilling the spar for steaming/deck light

Postby mike cunningham » Fri Dec 09, 2016 2:20 pm

Tom,

Good question which I am not qualified to answer. Having said that I went ahead and enlarged the 1/4 inch hole for steaming/deck light install about 3 feet above the halyard/lazy jack box on the F30. I had to go up to a 3/8 hole to get three 16 awg wires and 1/16 strain relief line through the hole. I also had to add 3 small holes for the screws to hold the new line guard. Frankly, I don't think anyone knows for sure what the implications are going to be. No question that drilling holes is NOT a good thing ...how much of not a good thing I dunno.

I look at the very large holes made to accommodate the halyard box and the halyard exits at the base of the mast above the gooseneck and figure I should be OK. I did carefully inspect one of the halyard exits and saw no obvious reinforcement. So I took a chance. I did note the halyard box plate (2/3 rds up the mast) has about 20 holes drilled to accommodate rivets. I assume the plate is designed to distribute the box loads. Seems like holes were not the big concern??

Anyway, more races and heavy wind to come so I'll keep you posted, ha ha.

As to the other to dos, everything went pretty well. I got the mast step nice and snugged up by wrapping the top hat with about 1/8 inch of silicone tape to close the gap which allowed the base to move. I realigned the tricolor and made a big improvement but it is still 5 degrees off. The only way I see fixing this is to go up the mast with the tricolor turned on and assign a far field observer to provide alignment feedback as I tweak the light alignment. It is a real pain.

One thing I have taken to heart is the use of diaelectric grease where connectors are mated. Especially, hard to get at connectors. One of the SSS electronics experts recommended dielectric grease for masthead RF connections. I also used it for the wind transducer connection and tricolor mating connector. I found a bit of corrosion on the male pins of my Raymarine transducer when I removed it form the masthead base. Not good. So I cleaned it up and applied plenty of dialectric grease to keep water out of there. I plan to do the same on my cockpit seatalkng connectors which are somewhat exposed on the weather deck.

Mike
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Re: drilling the spar for steaming/deck light

Postby Camino » Sat Dec 10, 2016 2:37 pm

Good one Mike - the mast on my F35 (p) has gobs of bolts and screws and rivets. It is a dunno however :lol: diaelectric grease is good - don't know with sea talk cables as those connectors have little o-rings built in to seal. Did you say which yard took your mast off?
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Re: drilling the spar for steaming/deck light

Postby mike cunningham » Sun Dec 11, 2016 3:46 pm

Used Berkeley Marine Center based upon a recommendation from another Freedom Board poster and SSS colleague who has a Freedom 36 in the Bay. Berkeley Marine was great plus a real causal attitude. The only downside is there are a lot of self helpers there, you'll spend half your time meeting people and talking about boats and whatever.

Re diaelectric grease and seatalkng connectors. I know they are supposed to be watertight but for whatever reason I experienced some leakage at one of the backbone connectors on the seatalkng connector block in the cockpit. This resulted in a small electrical fire in the vicinity of the connector and really freaked the delivery crew out when they saw this little ball of fire emerge in the middle of the night. They cut the backbone cable feeding the block and killed the wind and autopilot head for the rest of the trip. Fortunately I had a complete backup autopilot system so they did not have to hand steer for 1000 miles. Post trip inspection revealed quite a bit if corrosion around the male pins in the block which led to a classic short through the low resistance corrosion. Not sure what the technical term for this is but the area heated up fast and burnt hell out of the block before they got it disconnected. From now on I intend to use dialectric grease to reduce the chances this will happen again. I am also trying to find a way to better protect the block from spray. It is difficult to get it completely out of the cockpit due to my specific configuration.
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