Those who follow this forum will be well aware that Lexia lost her foremast and rig in last years OSTAR. We, that is Lexia and I, got back safely and had a new foremast built and installed by the then Atlantic Spars of Brixham, so quickly that I was able to set out again, although I later retired. Much of this is reported in this forum and Magazine Issue 63.
(I should perhaps write here that the foremast was 4" dia at the deck, not the 3 1/2 " that I reported at the time. It was sleeved on the lower section. The upper section was tapered almost to a very narrow dia and very whippy. Robin Blain of Sunbird Marine Services does not have any further technical specification.)
(The replacement foremast was made with a lower at 5" dia at 3 mm thickness with a 3 mm sleeve, and a top section of 4" dia 3 mm thickness unsleeved. It is thus stepped between the top and bottom but this step has a sloped collar to reduce any drag on lowering sail. This seems to work satisfactorily.)
I am now very seriously considering replacing Lexia's main mast, which like the foremast is original and 36 years old. It is not an easy decision, not least because it will be a significant cost, and also because it is impossible to state categorically that it needs to be replaced. (Sunbird Marine Services is not Boeing!) The only certainty would be if I don't replace the main mast and it does fail, and then I would be certain that I should have done something about it.
I should say something about my general approach to junk rig boats and masts. I am well aware that some, indeed many members make their own boats and rigs and masts, or modify existing boats with other rigs. This has not been my approach. We bought a Sunbird 32 which, although pretty old, was designed and produced commercially as a junk rigged schooner. I do not have the time or inclination to knit my own.
When it came to replacing the foremast I went in search of a commercial solution and that is what I will do for the mainmast. I am well aware that there are members whose approach to their mast ranges from setting out into the forest with a small axe and emerging with a large pole .... to manufacturing a mast and spars from carbon fibre.
If Lexia is to have a new main mast it will be from a commercial supplier and almost certainly in aluminium alloy.
A word then about the likely supplier. Charlie Hutton worked from 1968 to 1981 in the design office of Ian Proctor Metal Masts. In 1982 he set up his own business, Atlantic Spars, in Devon. In 2008, because he was 'getting on a bit', Charlie sold the business as a flourishing concern but then worked for the new owner as designer. This was the position when Atlantic Spars designed, manufactured and fitted the new foremast for Lexia in mid 2013.
(Almost incidentally, Atlantic Spars had previously made a new main mast for Dennis Sidebotham and Janvier Aquila, a similar sized junk rigged schooner and Dennis reported that he was pleased with the dealings and the result. Janvier Aquila is about the same age as Lexia and had, I think, a similar original Neeldlespar mainmast which came down in not very strong wind just off Plymouth.)
Later in 2013 Atlantic Spars went into Administration. The whys and wherefores of that are irrelevant to my story here I think.
Charlie and Dan, another employee of Atlantic Spars, have since set up a Brixham branch of Petersen Custom Rigging, a company based in the North East of England. I was impressed by Charlie and Dan in my earlier dealings with them and will probably throw in my lot with them again.
I think that we can take it as a given that Charlie Hutton knows a thing or two about aluminium spars.
Now some information about Lexia and her spars.
32' 6" LOA. 26' 4" LWL Beam 10' 4" Draft 4' 0"
Design Displacement 10,000 lbs. Ballast 3,600 lbs
Long shallow fin encapsulated fin keel and skeg mounted rudder.
Foresail 217 sq ft. Mainsail 337 sq ft.
Foremast originally 4" OD at deck, now 5".
Current Mainmast 5" OD at deck. By Needlespar 1978. Bottom part of mast understood to be sleeved. Top part tapered, swaged ? Very narrow at top. Top and bottom joined with insert sleeve and "glue" ? No more details currently available.
Robin Blain states that it is accepted that the foremast on such a boat has a harder life than the mainmast. Certainly on Lexia it was the foremast that failed, but on Janvier Aquila it was the main mast.
The cone through the deck for the main mast partners will reasonably accept a mast up to 5.5 inches. It would just accept a 6 inch mast but with very little clearance. The bottom of the cone might be trimmed to make it bigger but that would decrease its depth and hence its strength and its depth for any Spartight type compound.
Charlie has produced quotations for three possible design specs. All specify Al 6082 T6. Silver anodised.
Some general considerations.
Charlie can get tube up to a max length of 5 metres, so any mast made by him will be a construction.
5" OD available at 3 mm or 6 mm wall
5.5" OD available at 6 mm wall but not 3 mm wall.
The three designs are in increasing strength ( / stiffness ? ) but in increasing weight and cost.
The first design is the same OD bottom to top, which is more attractive than having a step, albeit a step with a tapered cone.
Tube 5" x 3 mm. 10.00 m above deck. 2.14 bury.
Internal doubler 3 mm to 3.66 m above deck.
Charlie's method for the doubler is to take a tube of the same OD and thickness as the mast and to cut a section out of the length of it. The doubler is then tightened to a smaller dia and greased and then hauled into the main tube using a TIRFOR winch. It will have a remaining split of approx 4 mm. The doubler is then joined to the main tube by drilling and rivetting both. As indeed are the sections of tube used to make sufficient length from the 5 m max length tubes.
I know that this statement on drilling holes in mast tubes will produce shock and horror amongst some of the members. (Shades of a Bateman cartoon!) Charlie's response is that such rivetting is not done near the partners. Also he states that anyone who states that one must never rivet a mast together might like to look out of the window of an airliner at the rivetted construction of the wing.
Charlie also fits an aluminium tube internal conduit for electrical wires, rivetted to the main mast but not rivetted near the deck. Again Bateman cartoon shock horror. I put to Charlie some of the suggestions made by members made by members as alternatives to stop electrical wires banging about inside the mast. His comment was that such solutions tend to be water traps which may encourage corrosion.
The second design is for a stepped mast with a bottom section of 5" x 6mm wall to 3.8 m above deck and a top section of 42 x 3 mm wall.
The bottom of the top section has a plug to fit the internal dia of the bottom section. The join is made with a plug with an upwards facing cone in the top of the bottom section.
The third design uses 5.5 " x 6 mm bottom tube and 4.5 " x 3 mm top tube.
My current inclination is to go with the first ie the cheapest and lightest design. It is the same OD as the original but Charlie will be at least as strong and certainly it will be at the start of its fatigue life. It is the same design as the mast for Janvier Aquila.
I am of course open to comments. And no I don't think that I will be setting off into the forest with my little axe, or knitting a carbon fibre tube!
If nothing else is achieved it may be useful for other members to know how this member is currently is addressing this issue.