mast splicing

[mikestevens]

Ah,
I see you are out of Annapolis.

[Douglas]

Hi Mike, T Y , for asking your questions on this forum. I am interested because I too am sleeving my 4.5" X 7.25" aluminum mast section in two places.

It was great to read Brian's reply, and that raised some questions for me too.

First question is what really is the need to taper both ends of a mast sleeve ?

Second question is what is the reason for using adhesive on the sleeves ?

Third, would there be any advantage to using oval head instead of flat head fasteners ?

Currently, I am copying a sleeved mast splice that I saw being assembled at a local boatyard, I have a photo of it, if you need it ?

I also need to order 4 new tapered spreaders , from where , I don't know . I placed a fax order one month ago, with Rig Rite, but have heard nothing from them, and after reading the Cape Dory forum, expect that my order has been sent to the round file, drats !

Douglas

[mikestevens]

Your welcome. Let's see. I hadn't considered oval head vs flat head. I guess I pictured oval heads because the flat heads would have to be countersunk and there is not too much thickness to the walls. In any case I would welcome any response on that issue. And yes, I would love a picture of it. my email is mike@exactimage.net.
As to the tapered spreaders, I have found JSI in FL to be a great resource. Perhaps they can help you too. (Dave Johnson [djohnson@newjsi.com])
Mike

[Douglas]

Hi Mike, I really like that we have such great sources of info available to us, on this forum, and I thank Brion Toss, for that,,,,, and on this occasion, Brian Duff too !

I discovered that there are heat-shrinkage and internal stress-tension problems associated with linear welding the sleeves in anticipation that the re-joined sleeve parts will fit "nicely" into the mast section.

Maybe that is why Brian Duff shys away from doing that, or maybe even for other reasons.

Since we don't have any riggers or rigging shops for sailing yachts, here in Singapore, I had to forage ahead with what knowledge I could find locally,,,, which wasn't much, drats !

I will try to contact JSI , or any other reccomendations from the forum, for the replacement spreaders, that I need , T Y .

Douglas

[mikestevens]

yes, this is a great resource.
I guess the idea of just bending the extrusion sounds easier than all that welding anyways. I can bring a piece of extrusion to a machine shop and have them bend it accordingly. this will be easier than having a friend bring down all his welding stuff.
I look forward to the picture of the splice.

Mike

[mikestevens]

Brian,
When you use flat head screw, that must mean you countersink them. Please confirm. Also,
1. How many rows of fasteners would you use on each side of the splice?
2. I think I understand the taper, but was wondering about the arch that I would cut out. Would it be steep or more rounded. Would I be removing more material that I would be leaving, for example?
3. Is the purpose of the taper to gradate the stiffness as to allow the bending loads to dissapate?

[Douglas]

Hi Mike and Brian , I was thinking of using oval head screws, for one reason only.

I have found that upon removal of flat head fasteners, the phillips head "cams out" all too easily,,,,,, where as the oval head has more "meat" at the driver bit insertion area at the phillips slots.

Sometimes for removal purposes, of a v stuck fastener, I use a center punch on the screw head skirt, after I have already "camed out" the driver slots, trying to remove it,,, and the oval head would give me more "meaty skirt" to pound on !

While on this subject , what is best chemical to use , to put on a "stuck" , ss fastener, to disolve the white powder, inorder to make removing the screw, easier ? Since caustic soda is used on aluminum, before anodizing to clean the metal, could it be used to remove the white powder around a corroded fastener,,,,, caustic soda, being a lye solution ???

Any knowledgable suggestions out there in rigging land ?

Douglas

[Russ L]

Hello all,
Good thread eh!
For a corroded & stuck fastener, try vinegar, not caustic, it can dissolve the white powdery stuff. If the mast is not anodized then a bit o' heat can work wonders.
On the subject of screws, oval & flat head can be considered equals mechanically, however oval are much more pleasing asthecially. Oval head screws can tolerate slightly different countersink depths and still look good.
On the practical side, you can assemble the splice and drill, countersink & tap without further disassembly. Pan head screws would normally require two step drilling (unless you are very brave and willing to try without making the tap hole too big) and bunch o' pan heads just doesn't look as nice.
The splice material taper AND rounded "taper bottom" are to prevent stress risers. It's a stress riser that caused the damage in the first place (the deck opening).

Cheers, Russ

[Brian Duff]

more important (IMO) than the fastener type, splice plate taper, or splice location, be sure that the mating ends of the two extrusions being spliced are a perfect fit. The ends must be square and true. The rig will not tune straight or bear compression properly if they joints are not perfect. take the time here to get it right. I spent 5 hours once until I was happy. Oh to have a large chop saw for masts !

Most mast splices are not glued, I am the only rigger I know that does this. My thought is that there are no disadvantages to the glue, but the possible advantage of a more even transition of stress is worth the effort of the gluing process. It is not necessary to use adhesives.

Flathead or Oval head screws are stronger because of the less dramatic angle at the bottom of the head to the shank of the screw, (they also offer less resistance to wind, and look better).