Samson Post - question/warning

Ask an Expert !
Do you have a question about any aspect of YM designed boats?

Moderators: Eventide Owners Group, Piskie, chris s

JFJ
Posts: 10
Joined: Tue September 6th, 2016, 12:07 am

Samson Post - question/warning

Postby JFJ » Mon September 26th, 2016, 2:46 pm

Hi All

During the storms over they weekend in Northern Ireland, Iris (26ft, Golden Hind) was cast onto the beech. The coast by her moorings is mostly shingle and rock - though the rocks can be up to some 4-5 feet across. Of course she hit a few of these, and lost some fibreglass underneath, which I believe I can fix.

Thanks to the members (about 10 brave souls), braved winds of up to 55MPH (by my nanometer) to get her off on the next tide, with me, with 2 ribs, and shore parties.

Several fine boats were on the shore, mine was the one at most risk of hitting others, should she have drifted, and so came off first. A lovely contessa is still there, 3 days later.


Anyway, this is not a story of my adventure in that respect.

The cause of the incident was soon spotted. The wooden sampson post had sheared at the deck. The wood seems hard still but the top part is gone. The head of the self tacking gear is also broken off (basically a whisper pole fitting, broken in half in the casting. The wood does not appear to be rotten - it certainly wasn't on the outside!

Question here is - what was the wood used in the sampson post? The post runs to the keel, and is painted below deck. I was thinking of replacing the top half (scarfed and collared) with a laminated oak and mahogany piece - perhaps an inch bigger squared. Your thoughts? Iris will have to come out this week for a thorough inspection underneath - and I likely won't get my last planned trip this year now- so I have time to think on this. The obvious option of a Stainless Steel post, with cross bracing underneath to the 2 roof members is a possibility, but could pose a different problem with a remade self tacker....

On the self tacker, as I have to get another one, I was thinking of making one out of spruce and oak laminate - this might give me some options with the stainless steel post... Any thoughts on this would be appreciated.

oh aye, the warning - check your sampson post this time of year- especially coastal moorings!


Regards
John F J

GHM
Posts: 16
Joined: Thu March 10th, 2011, 9:36 pm

Re: Samson Post - question/warning

Postby GHM » Thu October 13th, 2016, 10:06 pm

Hi,

Sorry to hear of your problems. You seem to be much calmer about it than I think I would have been.

Terry Erskine built all of the Gh26's except the last one which I built. I'm very surprised about the sampson post breaking. It was always felt to be massive and perfect for being towed by a lifeboat without problems. Much stronger than a cleat through the deck or a scarfed on new section. It was normally solid iroko, in one long piece, through the deck and down into the keel, with a 1/2" round brass pin driven in very tight underneath the first deck beam to stop it lifting up. I always cast the bottom end into the keel at the base, and bolted it through the half bulkhead at the foot of the bunks as well. So I would have thought you would have pulled the deck out first, unless there was a flaw/split or rot in the post around the deck area. There is a possibility that the pin was drilled too tightly and by driving it in hard (as they did), it caused a split. The hole in the post was sometimes drilled a couple of millimeters too high under the beam (an interference fit), and a big lump hammer used to drive the pin in. Even so, it seems to have survived a long time until now.

If it was me, and not having seen it, I would replace the whole thing as the original. After all there were some 260 built and it's the first time I've heard of a problem. You need to drive the pin out, release any fittings (screws/bolts/glue) attaching it to the half bulkhead, free it at the bottom end if necessary.

Re your other queries about the rig, I may still have some drawings for the various GH 26 rigs, when I can find the time to have a hunt around.

Best of luck.

Mark

JFJ
Posts: 10
Joined: Tue September 6th, 2016, 12:07 am

Re: Samson Post - question/warning

Postby JFJ » Fri October 21st, 2016, 9:15 pm

Thanks very much Mark.

I have chopped out the top of the post so far - the stump was rotten for about an inch into the break. I had to cut the pin under the deck - as you said, it was driven in under tension. the deck seams sound - the sampson post went through the bowsprit base. There was a piece at the back of the post faired into the back of the bowsprit too. I also found a pin above the deck, through the bowsprit, as well as several brass screws (all potential water sources)... I could get it out as the wood was fairly spongy, and a chisel did the leverage....

The little bulkhead makes it difficult to get at the bottom of the post. I cut the post about 6 inches down below the deck, and the wood appeared sound.

I believe that the issue stems from a SS bolt driven down from the top of the bolt, which had the swivel for the staysail boom... Water likely worked in and rotted the core - the edge to about half an inch was sound, though I can't find the top part of the post to check higher!

The post seems glassed in fairly heavily at the bottom, I doubt I could get it out without significant surgery!

I had a chat with a local wooden boatbuilder (Alistair Duffin), who reckons he can build me a new one, (likely going 3X4 inch, with the extra inch at the front, faired, as a separate 'shoulder', epoxied and pinned). The new ring for the staysail will come in at 90 degrees this time - from the back-side of the post, rather than top.

Re the Yankee - any help there would be great - the boat really cranks up in a 4+, but I think it could with a wee bit more in light airs ;)

I recorded big winds in the morning after the incident.... God knows what it had been overnight. I used to have a chain strop, and replaced it with a rope one (ironically to protect the wood!) - I think perhaps the rope strop rode up the post a bit.... combined with the rot, and the sea state we might have got a snap/jerk on the strop...

My calmness stems from having owned an early 70's motor sailer for the last 10 years, and if anything on her could break, it did! I got used to trying some stuff myself!

Regards
JFJ

User avatar
Fiddler's Green
Posts: 180
Joined: Wed March 1st, 2006, 12:58 pm
Location: Essex
Contact:

Re: Samson Post - question/warning

Postby Fiddler's Green » Wed November 16th, 2016, 10:29 pm

The story of the samson post is very alarming, I have one made of Afromosia and 4 inch square, so far so good!

A friends however is in real need of tlc and I have sourced a 3 inch square length of iroko to replace his, it was oak but spilt down halfway to the deck and looking very suspect. I blame it on the 1nch pin someone fitted accross it, way too large.. and the fact that the end grain on the top was left unprotected.

On the work boats I used to man on the London river the tops of posts had brass plates with mastic under them to prevent water getting into the end grain. A lead cap is good too, if masticed on. Or you have to ensure the end grain is well coated with a good coat of something every year.. I use Sikkens!

To prevent the chain chewing the posts we used shaped castings of brass let into the corners. I have adopted this for my samson post, to protect it from the chain, but today I have a heavy strop with a stainless chain hook on the end to latch ont he chain instead, so the chain does not touch the post.

Seen some posts half sawn through by chains!

So pleased Iris has been recovered and is not too worse for the experience.

The sheathing should be easy enough to repair using epoxy, once all has dried out!! Apply a coat of epoxy straight to the sanded timber.. Then you can lay on a new layer of glass cloth, fixed at the edges with masking tape..... roll a coat of epoxy through it and allow to set.. Fair it off with a sander before giving a topcoat of epoxy, and you can thicken that coat slightly to fill any weave, 3 coats of epoxy and it will be as sound as before, if not more so!

Just need the temperature up to 15 C to ensure it goes off! Job for the spring, if you cannot get under cover and warm it...

regards,
John
Proud owner and builder of 'Fiddler's Green'

JFJ
Posts: 10
Joined: Tue September 6th, 2016, 12:07 am

Re: Samson Post - question/warning

Postby JFJ » Mon January 2nd, 2017, 12:05 am

Saga continues.....


I dug out the old stump of post, including bronze pins (though they got mangled in the process). I cut the old post about 8 inches below the deck, and inspected it for signs of rot. non found there.

IMG_20161016_134951.jpg
20 KB
IMG_20161218_144436.jpg
20 KB
IMG_20161016_135005.jpg
IMG_20161016_134951.jpg (22.02 KiB) Viewed 1080 times

IMG_20161016_135005.jpg
IMG_20161016_135005.jpg (23.73 KiB) Viewed 1080 times


OK, so I got a new top of post made, laminated out of 3 1 inch pieces.
Got some 13mm Phosphor bronze rod, for the to pin the post, and provide a spike for the post....

drove the pins through...

a got a couple of scrap pieces of Iroko and a piece of mahogany (for in the cabin - through the bulkhead) as cheeks
IMG_20161218_144436.jpg
IMG_20161218_144436.jpg (20.33 KiB) Viewed 1080 times


I trimmed the old sampson post at about 8 inches below the deck

After some trimming, I dropped the new post sum through the deck, inserted and hammered home the bronze pin to the deck member in front of the new post piece. The post was wrapped in 3 'rings' of Sika, to fill any voids between deck hole and post - the excess would be trimmed off, when set. I did not upset the fibreglass round the hole. The post drips through the bowsprit and deck.

Reattaching, I through bolted the old post post on one plane, with another through bolt at 90 degrees into the new piece - through the cheeks. I used coach bolts (2 inch (through the mahogany) and 5 inch through the iron respectively) to in tie the timber. The mahogany pins the bulkhead to both the old and new posts. Each cheek and the bulkhead is beaded in Sikaflex as well.
Each piece of timber was traded with durabond wood sealer before installation. Each hole drilled for pins/coach bolts was partially filled with ska before screwing home.
Last edited by JFJ on Mon January 2nd, 2017, 10:54 am, edited 2 times in total.

JFJ
Posts: 10
Joined: Tue September 6th, 2016, 12:07 am

Re: Samson Post - question/warning

Postby JFJ » Mon January 2nd, 2017, 12:21 am

IMG_20170101_165031.jpg
IMG_20170101_165031.jpg (14.06 KiB) Viewed 1077 times
IMG_20170101_165411.jpg
IMG_20170101_165411.jpg (16.79 KiB) Viewed 1077 times
IMG_20170101_165418.jpg
IMG_20170101_165418.jpg (15.69 KiB) Viewed 1077 times


You can't see it in the pics, but a wooden shim was hammered and sikkaed in between the cheeks and deck rib. A Bronze pin was driven through the sampson post and wedged to the deck rib also (as was in before).

forgot to mention that the coach bolts on the mahogany were countersunk - I don't want to crack my head in my master cabin!

1 coat of sickkens applied to date. Its a bit cold outside, so will be left for a while (covered, of course)

TODO - The bronze I got is slightly larger than that originally in place for rod through the bowsprit - I need to drill out a little more of the bowsprit to fit the through pin there.


TODO - paint up the wood in the anchor locker.

TODO - make fixing for the yankee gooseneck. The pad which can be seen glued to the sampson post face will be the mounting to which the fitting will be attached.


I hope that this is enough :)
Next up, the keel.

User avatar
Fiddler's Green
Posts: 180
Joined: Wed March 1st, 2006, 12:58 pm
Location: Essex
Contact:

Re: Samson Post - question/warning

Postby Fiddler's Green » Mon January 2nd, 2017, 11:00 am

Hi JFJ,

The extent of the rot is alarming. Seems the timber was not half as durable as it should have been.

The laminated Iroko should be much stronger.... and the glued on cap should stop water ingress into the end grain of the post itself!

I realise now that of course the hull is GRP so normal GRP repairs not my suggested repair regime which was aimed at ply!

Good luck with the rest of the repairs, hope to cross wakes next season!

Regards,
John
Proud owner and builder of 'Fiddler's Green'

JFJ
Posts: 10
Joined: Tue September 6th, 2016, 12:07 am

Re: Samson Post - question/warning

Postby JFJ » Mon January 2nd, 2017, 7:32 pm

Fortunately, both the hole in the bowsprit, and the hole through the deck were coated - the bowsprit in rubberised gloop, the deck hole seems to be edged with fiber glass cloth of some kind. As a result, both the ply deck, and the bowsprit showed no sign of softness (thank God!). Hopefully, the new pieces have not disturbed the setup significantly. I put the rot down, most likely, to the swivel eye, which was drilled into the top of the old post stump, and the fact that the cross bronze pin was much higher up the shaft of the post. The strop must have rode up a bit to provide the necessary leverage. There is no chance of that repeating - the pin is perhaps 3 inches lower, (Davey Jones has the original, so I can't check!), and the new post has the pad to which I will attach the rebuilt staysail boom on a vertical face for water runoff.

BTW
If you are trying to fit a bronze pin, and cant - try popping it in the freezer. 13mm pins are more like 13.4, at room temp. They do not shrink much, but it does seem to help. Need to wrap them in a cloth if you have any distance to carry them as they gain/loose heat very quickly.

BTW, if someone has the sail dimensions for a GH26, it would much appreciated. I have an offer of a S/H jenniker which might work.
My mast is 29 ft, and the bowsprit is approximately 4ft.

Regards
JFJ

User avatar
Fiddler's Green
Posts: 180
Joined: Wed March 1st, 2006, 12:58 pm
Location: Essex
Contact:

Re: Samson Post - question/warning

Postby Fiddler's Green » Tue January 3rd, 2017, 12:52 pm

Hi JFJ,

As far as I know the sail areas are the same as the Eventide 26. the drawings were, as you can see on the GH page of the Gallery, a straight copy with just minor alterations to chine and ballast later. (OK some had stepped cabin tops too...)

I have a 200square ft Genoa on roller gear. A little larger than the 160 sq ft shown on the drawings, works better, as it moves the C of E forward!!

Good tip with the bronze pin!

I attached a separate s/s post and gooseneck on top of my bowsprit about 1 ft back from the tack, that works a treat.

Regards,
John
Proud owner and builder of 'Fiddler's Green'


Return to “HELP ?”

Who is online

Users browsing this forum: No registered users and 1 guest