Holes in the mast

kpgraci

kpgraci

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Jun 12, 2010
936
Oday 22 Orleans Marina, NOLA
This for you structural engineers out there. To install a steaming light I need to drill a hole in the mast big enough to fish a wire through, so I'm thinking at least 3/8 inch, maybe bigger. This hole would be just north of the spreaders, say a foot.

Now the mast on the Oday 22 is not as robust as some of yours so I have concerns about its structural integrity.

I see two options, one would be to run the wire external to the mast, the other would be to place the hole in location that would least detrimental.

So assuming I drill the hole, and knowing the profile of a typical mast (egg shaped) what is the best place from a structural integrity standpoint to place the hole?

On the leading edge (best for the light)? On the side? Somewhere in between?

Or am I worried about nothing?

...and what are the options for an external wire or it that even an option I should consider?
 
thinwater

thinwater

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Mar 26, 2011
3,962
Corsair F-24 MK I Deale, MD
A critical factor is that the hole is NOT in a key critical failure location; the load on the mast is not the same everywhere, though the section is. So long as you can stay 1-foot away from the spreaders, a 3/8" hole for wire is commonplace. Also, fore-aft stress in that area (near deck fore-aft is more problematical, depending on mast design) is less critical in that area than athwart ships, so that is good.

Leading edge, 2' above the spreaders should be good and is common. Bevel the hole, inside and out, to protect the wire (placing it in tubing is good too).
 
M

markwbird

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Nov 26, 2012
1,654
C&C 40-2 Berkeley
3/8" hole in mast

A 3/8" dia. hole located on the front of the mast a foot above the spreaders is fine. It will have a nearly negligible impact on the strength of the mast. The stress on the mast when sailing does not come close enough to being maxed out to cause a tiny hole like that to put it over the top. (no pun intended)
 
justsomeguy

justsomeguy

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Feb 20, 2011
8,062
Island Packet 35 Tucson, AZ/San Carlos, MX
3/8 inch? Will that leave enough room to install your grommet to protect those wires?

Ah, just re-read your post. You'll probably want to install the smallest grommet that'll allow your wires to pass through, and that grommet will determine the size of your drill bit.
 
kpgraci

kpgraci

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Jun 12, 2010
936
Oday 22 Orleans Marina, NOLA
I'm trying to imagine the forces that are placed on the mast. As a masthead rig, the jib force it seems is countered mostly by the upper and back stays, with the mast getting compression force. The main applies a more even force through the length of the mast. Without lower stays I imagine a strong gust would cause the main to bend the mast in half midway. It seems a lot of broken masts happen at the lower stays, but this probably requires the top stays to fail first. Well if stays fail all bets are off.
 
Rick Webb

Rick Webb

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Jun 2, 2004
3,650
Hunter 23.5 Fort Walton Yacht Club, Florida
Another Option

A boat that size it is not unusual to have the steaming light at the top of the mast. No need to add another hole to the mast actually there would be at least three holes one for the wire and holes for the fasteners.
 
seadaddler

seadaddler

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Dec 19, 2006
5,832
Hunter 36 Punta Gorda
Holes

I don't see any reason worry about very small drilled holes in the mast
unless there are wires already in a tube on the front of the mast.
I have seen many a drawing a mast with different places to run wires or halyards.
My steaming light on my H-36 is at the top and also have seen steaming lights
up maybe 3/4 the way up.
Can you check and see where wires are coming out the bottom of your mast.
 
kloudie1

kloudie1

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Nov 6, 2006
10,214
Hunter 34 Mandeville Louisiana
I am with the consensus, Ken .. a hole that is "small" in relation to the mast dimensions and not too much bigger than the wall thickness (about 3 times in this case) will have little effect..
 
B

Benny17441

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May 24, 2004
7,213
CC 30 South Florida
I side with Rick, at your mast height having the steaming light at the top of the mast would work best. There are some fixtures that double as steaming light and anchor light, they have a second bulb that allows for 360 degree illumination. Go LED for power saving, brightness and longevity.
 
Joe

Joe

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Jun 1, 2004
8,318
Catalina 27 Mission Bay, San Diego
A single 3/8 hole isn't going to hurt your mast.
 
Anonymous 121765

Anonymous 121765

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Jan 6, 2010
1,520
KP,

Another bit of good news is that structurally speaking, a curved sides by design have higher structural integrity than a flat side narrow width & a long length. A 3/8" hole will not compromise the integrity.

I can't remember a time when I saw a fallen mast that bent & snapped at the curved ends, only the flat sides.

CR
 
Daydreamer

Daydreamer

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Oct 19, 2009
97
oday 22 Lake New Melones
The mast on my 22 is no longer the original gold anodized one. I am not sure where it came from only that it was on the boat when I got it.

That said, the deck/steaming light is mounted right where you are thinking of mounting yours and has not been a problem or worry for the 6 years I have owned her and 20+ knots of wind I have sailed her in.

Instal it and enjoy :)
 

Attachments

kpgraci

kpgraci

.
Jun 12, 2010
936
Oday 22 Orleans Marina, NOLA
Daydreamer said:
The mast on my 22 is no longer the original gold anodized one. I am not sure where it came from only that it was on the boat when I got it.

That said, the deck/steaming light is mounted right where you are thinking of mounting yours and has not been a problem or worry for the 6 years I have owned her and 20+ knots of wind I have sailed her in

Instal it and enjoy :)
Click to expand
I have the original gold anodized mast. I wonder what happened to yours. :eek:
 
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