1 Topic by rbporter (edited by rbporter 2006-07-15 05:21:09)

  • From: Massachusetts
  • Registered: 2006-03-07
  • Posts: 97

Topic: stemhead casting/forestay tang

The forestay tang on my cast aluminum stemhead just doesn't look up to carrying the loads  a roller furling headsail  will exert on it. Being alumminum, or some alloy thereof, it shows corrosion from the galvanic action with ss forestay turnbuckle. The alum. is not smooth with a dull alum. oxide, but dull and chaulky/porous from this corrosion. I have seen one other co26 where the sockets for the bow rail  tubes where so corroded to make them nearly worthless. The boat has been on the trailer since I have owned it and I don't feel comfortable rigging and sailing it with things as they.  This is not the only reason she is not in the water this year but  this is one of the items to be checked off by launch day.
Aprreciate any thoughts...

  • Registered: 2005-09-22
  • Posts: 17

Re: stemhead casting/forestay tang

Suselle sports her original casting which took her to the Bahamas and back, up and down Lake Ontario many times and she's ready to do it all again. Are there any instances of this casting actually failing?

  • From: Ottawa, On
  • Registered: 2005-03-10
  • Posts: 353

Re: stemhead casting/forestay tang

If you remove the casting, you'll probably get real scared....  When I took mine off the space underneath the casting (it's not all solid, there's a pocket underneath) was full of white powder - dissimilar metals being the alum and ss machine screws that bolt the sucker down. 

I'm going to build a tang out of 316 and just mill the stock one off. 

The whole setup as it is makes me really really nervous, like I've said this is on par with Mirage quality....

stefan_d's Website

  • From: Massachusetts
  • Registered: 2006-03-07
  • Posts: 97

Re: stemhead casting/forestay tang

stefan-d
Thanx for your response..
There must be many co26 owners with either this problem or problem soon to be.
The hole on my forestay tang is oblong. This is not good on a boat that I feel has not got  a lot of use, hence my suspect of the compromised strenght.
VARUNA, as I have observed, has a ss plate with a welded tang as you suggest. It is screwed/bolted  down using the existing  four holes. It looks very substantial. This as you note may be the path to fools paradise if what is anchoring these bolts may not be much different then what was anchoring the bolts of the ceiling panels of the "Big Dig" tunnel (Boston thing, US tax payers $'s). Without having seen it I wonder if this area can be filled with an epoxy mix. With enough surface area this should spread out the load  to every surface  of the hull and deck it touchs.

5 Reply by stefan_d (edited by stefan_d 2006-07-15 10:37:12)

  • From: Ottawa, On
  • Registered: 2005-03-10
  • Posts: 353

Re: stemhead casting/forestay tang

Thats what I did - removed the stem fitting and boxed in the glasswork on the forepeak (from the inside) to make it real substantial, and then filled the 4 bolt holes with epoxy from the outside, so now the whole thing is solid.  It was pretty delaminated when I took things all apart.  The stem fitting is like the chainplates - needs rebedding and I'm sure that this is a forgotten item on most boats.  I would think it spends a fair amount of time in the water or wet, and the damage was 30 years done on my boat........

Original setup is 4 thru  bolts with backing plates to port and starboard - it's not 1 backing plate.  I'm making 1 plate with 4 holes.......

The forestay hole is pretty egg shaped on my casting too - this is one of those things that will give you no warning of failure.  It's like rod rigging, you don't have any warning signs about it happening until the mast is in the water.....

stefan_d's Website

  • From: Vancouver, B.C. Canada
  • Registered: 2005-05-06
  • Posts: 304

Re: stemhead casting/forestay tang

Hmmm, my previous owner re-rigged everything...and moved the forestay forward an inch or so, re-drilling the hole in stemhead, as the original one had CRACKED!!!  So....that does indicate a problem to me too...and I too was going to get a new one made in stainless, with two holes, for both roller furling and optional forestay for hank-ons.

“You get a boat for only one reason, because you want one.  If you’re worried about being practical, forget boats.”
  • Registered: 2005-04-08
  • Posts: 35

Re: stemhead casting/forestay tang

My rigger was insistant about making me a stainless steel fitting for my stemhead, the old one had cracks in it and the attachment hole was really badly wallowed out. We actually remade the entire nose of the boat making it stronger at that point before making a flat thick piece of stainless combo anchor roller. He placed a strap of metal over the stem and down the centerline to bolt to. It was overdone but I sure don't worry about that part of the boat anymore. I can send a digipic if you would like. I can now see my rigger in town and not want to choke him for all the money he charged me for that and other repairs made to the boat.

  • Registered: 2006-07-30
  • Posts: 2

Re: stemhead casting/forestay tang

Hi Bluehair,
I recently purchased the Coba in Powell River ans she has the same issue with her stemhead.  Can you please email the picture that you mentioned regarding the SS upgrade?

Thanks.

  • From: Montreal
  • Registered: 2005-04-22
  • Posts: 259

Re: stemhead casting/forestay tang

Unfortunately there does not appear to be an inexpensive solution for this problem.

My stemhead casting is aluminum and shows cracking where the pulpit enters the casting.  However, everything else SEEMS to be sound.  A bit of wear of course but otherwise OK.

On my boat the stanchion bases are all painted bronze castings.  Perhaps this might offer us a partial solution.  Maybe we should approach an outfit that casts in bronze and make stemheads for a number of boats at the same time.  Aluminum casting does not appear to be as common so that is why I would consider bronze. 

Alternatively, were we to prepare suitable drawings, we could have someone mill a new stemhead out from an aluminium block (or any other material for that matter. 

Unfortunately both options are costly.

I know other owners have had new stemheads prepared.  How exactly was this done?

Christopher

p.s.  If we were REALLY clever then we would take the opportunity to add anchor rollers and anything else that might be practical to include in the stemhead fitting at the same time.

  • From: Ottawa, On
  • Registered: 2005-03-10
  • Posts: 353

Re: stemhead casting/forestay tang

I was going to machine a new stemhead out of aluminium (this is what I do for a living) but decided that it would really be just too much work and costly materials-wise to be worthwhile.  I'll be making an inverted "T", from 316 SS, to replace the tang on the casting, and thru bolt it along with the casting (with original tang removed).  This will be plenty strong and not as susceptible to "no warning" failure than cast alum.....

stefan_d's Website

11 Reply by idealpowers (edited by idealpowers 2006-08-03 06:39:48)

  • Registered: 2006-04-13
  • Posts: 19

Re: stemhead casting/forestay tang

Stefan   

Varuna has the forestay tang you are talking about.  It is certainly sturdily made and appears to be bolted through the original aluminum casting, as no through bolts show in the forepeak.  Tim Hendley (who bought the boat from Tania Aebi) had the tang made, as says he put a sheet of plastic between it and the aluminum casting to inhibit corrosion.  Good luck. 
Sam

p.s. I uploaded a photo to the 'maintenance and technical' section of the gallery

  • From: Barrie, Ontario, Canada
  • Registered: 2005-10-10
  • Posts: 237

Re: stemhead casting/forestay tang

  • Registered: 2005-04-08
  • Posts: 35

Re: stemhead casting/forestay tang

I took some digipics of my new front end, unfortunatley they are too large to upload. If anyone wants to have them I will send them individually.

  • From: Victoria B.C.
  • Registered: 2006-03-11
  • Posts: 171

Re: stemhead casting/forestay tang

I just spoke to a rigger today about maybe adding a solent stay.He mentioned that the mast head fitting is also aluminium.They live in different enviroments,but would'nt they be subject to the same stress.The rigger suggested dye testing,unless of courseyou have an obvious problem.I thought the original boat had the fore stay somewhat inboard,which could be stronger.Building something that ran down both sides of the bow in stainless would look good,be extremely strong and also require  a talented fabricator.Would also offer some wharf and anchor pronging protection.

  • From: Massachusetts
  • Registered: 2006-03-07
  • Posts: 97

Re: stemhead casting/forestay tang

What about having a duplicate stemhead with tang refabricated out of bronze. A female mold could easily (easily for someone who has done this sort of thing before) be made for a bronze poring. The result I trust would be like the one piece stemheads on the Cape Dorys. My stemhead is in pretty good shape except for the oblong shape of the holes for the forestay. I plan on taking it off, rebedding it at least (I'm thinking as I'm going on here) and possibly taking  it to a foundry to get some idea on the above.

  • From: Montreal
  • Registered: 2005-04-22
  • Posts: 259

Re: stemhead casting/forestay tang

Happy autumn all! 

I am reviving this thread because my boat is a victim of a haulout injury.  During haulout, the forward strap slipped on my boat and the whole thing dropped -- fortunately back down into the water from about 4' up so no damage to the hull other than some gelcoat scuffing.  However, and unfortunate for me and the boat, my pulpit was a victim of the strap and is now a piece of twisted wreckage.  Although the aft bases of the pulpit appear to be sound with no apparent deck damage, the aluminum stemhead fitting has been broken at the pulpit base.

All that to say, I am now in the market for a new pulpit and stemhead.

As part of my general boat bronzing project, if I am to fabricate a new stemhead then I would prefer it in silicon bronze.  (Bronze is actually easier and cheaper to cast than is stainless). 

Is anyone else on the market for a stemhead?  Has anyone experience with casting one?  Does someone have a mold?  And finally, what wish-list things should I try to incorporate?

My current list includes:
* changing from a three-post pulpit to a four as on the newer Contessas
* incorporating a step forward of the forestay for those days one must go over the bow to get ashore
* adding at least one roller or rubbing surface for anchoring
* adding plating at the stem to prevent damage from a swinging anchor

  • From: Napa, California
  • Registered: 2007-07-16
  • Posts: 41

Re: stemhead casting/forestay tang

I've had a fairly significant amount of experience with various 'castings' for parts and for a small run or a custom one-off it's usually cheaper and better to make up a stainless steel weldment of the fitting in question. If you can supply accurate dimensions almost any good fabricator can build a new SS stemhead for around $120-160, slightly more if you want some anchor rollers. We just received a quote of $240 for a pretty exotic stemhead fitting on the new 26's we're planning on building that has two rollers with fairleads for dual bow anchors.
I personally don't trust castings of any kind on a cruising boat as even the best can fail without advance stress warnings. I especially hate cast lifeline stanchion bases which corode from within until it's to late.
On the 26's the stemhead fitting is unfortunately used to cover up what it the single hardest area on a GRP hull to finish out. The easy way out is to bury the joint under a big 'fitting' that hides all the ugly stuff underneath as Stephan pointed out above.

gww25's Website

  • From: Chesapeake Bay
  • Registered: 2006-09-14
  • Posts: 79

Re: stemhead casting/forestay tang

I'm looking at replacement of the stemhead as well as, along with a general upgrade to rigging.  A fabricated SS316 1/4inch stemphead with integrated bow roller priced out at $450, but labor ran to about $1,800 (!).  That stopped me in my tracks, even though I think it is a necessary change which will give me more peace of mind when I'm out (like last Saturday in Force 6 on the Chesapeake Bay with gusts to near gale...that was COOL!).

I did go with what may be the most reputable and trustworthy rigger on the Bay (and therefore pricey), but perhaps you get what you pay for?  Any advice on the pricing?

19 Reply by gww25 (edited by gww25 2007-10-23 12:39:04)

  • From: Napa, California
  • Registered: 2007-07-16
  • Posts: 41

Re: stemhead casting/forestay tang

gww25's Website

  • Registered: 2005-04-08
  • Posts: 35

Re: stemhead casting/forestay tang

In rebuilding my boat I had access to two riggers, one guy, a young French Canadian, looked at the old
cast aluminum fitting and said it was fine. The hole for the pin was eggshaped and there were some cracks around the edges.  The other rigger who was busy selling me many other upgrades to the rig insisted on rebuilding the nose of my boat, including making a stemhead fitting. Now that I have the benefit of hindsight, he was correct.  The main things  he wanted were to beef up the stem using a good fiberglass man which included modifying the stem itself with a groove to place a tang, which is part of the new stainless fitting, down the front to bolt through. The old aluminum casting was probably the source for some leaks as well.

He gave me an anchor roller too. The fitting is all one piece and has to be much stronger than what was there to begin with. At the time I felt it was overkill but after reading all of the trepidations by others on this site about the original build quality for this area of  the boats I feel he was the best choice. He has had the benefit of seeing many dismastings and was highly recommended by the surveyor I used. Both the surveyor and the rigger were in general very positive about the boat and her quality.  I know myself well enough to know that had I left the old fitting as was, I would have spent way too much time worrying about it, and so consider the money well spent. I used the old pulpit
even though he was very insistent about that too.  You gotta stop somewhere.

Having the attachment point for the headstay inside the extreme front has a slightly protective quality and is prettier too.  Keeping the lines of the boat  completely original is important to our classics,  but way out in the gulf those things don't really mean too much.  I bet you could get that kind of a fix for less money than a one off casting.
Fiberglass is much easier to cast than silicon bronze. I finally got the pictures to post on the site.  Good Luck!

  • From: Napa, California
  • Registered: 2007-07-16
  • Posts: 41

Re: stemhead casting/forestay tang

You'd think that after all of these years somebody would be making replacement fittings for a boat as popular as this.

gww25's Website

  • From: Montreal
  • Registered: 2005-04-22
  • Posts: 259

Re: stemhead casting/forestay tang

How crazy an idea would it be to hang a short bowsprit on the boat?  Say 1 metre or so?  This would facilitate rigging the boat with a staysail as well as the jib.  In addition, with a bowsprit, anchor rollers are a snap.  A benefit would be that the rig center of effort would move forward, reducing weatherhelm. 

The devil is in the details of course as this would not be an inexpensive mod.

23 Reply by rbporter (edited by rbporter 2007-10-24 12:46:57)

  • From: Massachusetts
  • Registered: 2006-03-07
  • Posts: 97

Re: stemhead casting/forestay tang

I have read of other co26's falling between the straps. The fellow who hauls my Cape Dory and any other keel boat, ties a lenght of line between the two straps  to prevent them from slipping outwards. Simple enough to avoid tragedy or near tragedy.
Chris, I am glad to hear it was from only four feet....

  • From: Hamilton, Ontario CANADA
  • Registered: 2006-04-06
  • Posts: 148

Re: stemhead casting/forestay tang

jcfoto's Website

  • From: Montreal
  • Registered: 2005-04-22
  • Posts: 259

Re: stemhead casting/forestay tang

Good day all!

Before everyone slags the guys who hauled my boat, I learned a lot today about what went wrong.  First, the boat fell only a few feet -- the keel was still in the water when the strap slipped. 

Second, it is customary practice to tie the slings together at this club.  However our water levels are very low and this made it difficult for the crew to board the boat.  Their plan had been to raise the boat a bit, and then board and tie off the straps before completing the lift.  Unfortunately, the strap slipped before someone could board.  That no one was aboard was probably a good thing as the frames supporting the mast collapsed during the fall, adding to the chaos.

Third, it may be that I contributed to the problem -- my mast had been unstepped and was mounted on tall braces on deck.  The height of the mast above the deck forced the slings to be longer, thereby allowing them to move a longer distance (such as towards the bow) before the forces on the sling resolved towards the crane spreader bar.  I knew the mast supports were unnecessarily high but was too lazy to cut them down.  Hindsight. 

Bottom line is this was an accident, and the outcome could have been much worse. 

Instead, I have some opportunities.  I have learned a lesson and my new mast supports will not give me standing headroom in the cockpit, assuming I make them at all.  The mast is on a rack for this season and today I fashionned a ridge pole from the boom and the spinnaker pole that rests about a foot above the cabin top.  I look forward to a snowy winter to test this arrangement.

I also know that I need a new pulpit.  This may be my opportunity to switch from a three legged pulpit to a four legged pulpit.  (Is this worth the trouble and expense?  Are four legs more stable than three??)

And lastly, the stemhead needs work and possible replacement.  As a minimum, it was already on my list to rebed next season so I now have an excuse to remove it.  (Boat looks good beneath it BTW).  In addition, this may be my chance to have a new stemhead fabricated to replace the aluminum casting.  In the ideal world, I would also redesign the stemhead to incorporate better chocks, anchor rollers, etc.  I hope that this will be a fun winter project.

Anyway, I appreciate everyone's input on the dream stemhead -- it is not every day one has the excuse to reengineer this part of the boat.

Cheers!

Christopher