Mounting a new mainsheet block on my 81' DS2

[mike31416]

I am replacing the mainsheet fiddle block on my 1981 DS2 with a Garhauer Mainsheet Standup Swivel Block. I will need to drill new holes into aft end of the centerboard trunk. Does anyone know if there is sufficient blocking to accept new holes. I was planning on using stainless steel wood screws.

If this is not an option then I suppose I can try this:

http://forum.daysailer.org/forum/viewtopic.php?t=3686

Thanks,
Mike

[mike31416]

I found a solution from Rudy at D&R Marine.

Rudy said:


THERE IS A BRASS PLATE IN THE FIBERGLASS WHEN THE BOAT WAS BUILT--SO YOU CAN DRILL & TAP INTO IT. THIS WOULD BE THE BEST WAY.
1/4-20 TAP #7 DRILL
REGARDS RUDY

[TIM WEBB]

That adapter has served me well for several seasons now. When I got the new standup block from D&R, for some reason it never occured to me to call Rudy and ask how to install the !@#$ thing! DOH!

I think it was 4th of July weekend, and I needed a solution NOW, and the machinist next door to our shop just happened to be in his shop. He took pity on me when I showed him what I was trying to accomplish. He did in about a half hour what it would have taken me all day to do! <grin>

- be nice if they would include that instruction in the package when they ship the fiddle block, but I realize that thing isn't DS-specific ...

[mike31416]

Worked fine but…

I placed the new holes in line with the beam and keel of the boat. The aft and forward holes had a good bite into the brass plate. The starboard side also had a good bite. The port side went in too easy and may only be fiberglass. I screwed in all four bolts and the port side tightened as much as the others. I don’t think there will be an issue since three of the 1/4 bolts are in solid, but I will keep an eye on it.

Mike

[GreenLake]

Will three bolts hold? You can estimate the force for normal use quite easily. Assuming that your own pull on the line will be below 100lbs, the total force is that, times the number of parts that connect there. With a fiddle block that would be 4, so 400lbs would be the maximum you'd expect in normal use.

With forces in that range, I suspect, you might never know that you effectively only have three bolts, but you have already used some of the redundancy in the design...

Worst case would have the main sheet cleated and then an accidental gibe or sudden gust or something slamming into the sail (or the boom hooked by a competitor in race).

I would stay away from the Florida 120 or Texas 200 though...

[mike31416]

The base place that comes with the block is about 1/8" thick stainless steel. The three solidly mounted 1/4" bolts will hold it in place and I don't think the base will flex. Something else will give before the block's mounting does.

The original block base plate uses four 3/16" bolts and the mounting plate is 1/16" thick.

I will watch to see if the block base moves and check it with the rest of the rigging inspections.

This gives me something to do while I am cruising on a warm summer day

Mike

[GreenLake]

The original block base plate use 4 3/8" bolts and the mounting plate was 1/16" thick.

I assume that's a typo for 3/16"? 3/8" would be truly massive....

I'm also not going on the EC 120 or Texas 200, as I have a similar spot I'm "watching" in my rigging - have been watching for many years now... so I know the feeling

Like yours, it's something where making it "perfect" would be a royal pain and seems out of proportion to the strength required...

[mike31416]

You are correct it is a typo, I will update the post. The line should read:

The original block base plate uses four 3/16" bolts and the mounting plate is 1/16" thick.

Yep if you always require perfection you will never get there.