Aluminium Mastprofil

Which spar is it?

A customer wants a jockey pole for his S 30 cruising square metre boat for spinnaker sailing at closer angles. Together with matching eye plates to hang on the side of the mast this is no big deal. The boom and fittings are requested from the leading mast builder Seldén via the Hamburg agent Herman Gotthardt. Seldén probably supplied the rigging for the S 30 in the 1970s.

An email from the manufacturer in Gothenburg states: “Due to our records it appears that two mast profiles were used for this type of boat: E 170/115 and D 137/113. I obtain the order number of the eye plate that are supposed to fit with both profiles. Order, pick up, pay, press eyeplate on the spar, drill holes, rivet it. Done. Great, that’s easy.

Draft of an old Seldén spar catalogue

If anything, it is a P-profile, which is not available in 170/110 at Seldén – photo by Swedesail

Owners advice part 2: Research in Sweden

A brief look at an old Seldén mast brochure at my office reveals that this cannot be. The S 30 has a teardrop-shaped P-profile. An E or D cross-section does not match to what I know of  the S 30. So I ask the owner to measure lenght and width of the spar profile and make a template right away. The profile is 170 mm long and 110 mm wide. Unfortunately, Seldén never made a 170/110 mm profile. Being busy with such particulars already, I am eager to learn which spar the boat manufactured by Fisksaetra Varv in Sweden has for my further advice to other S 30 sailors.

Is it possibly one of the English Proctor rigs popular at the time? After enquiring at further Swedish contacts, it turns out to be a “Gullmars” spar, whose manufacturer has long since closed down. There are neither documents nor parts available. So a stainless steel plate has to be obtained, a metal worker needs to bend it accordingly, cut it out, drill it, deburr it, weld on the eyes and finally polish everything. An expensive custom solution.

profile of the spar, obtained by a template

The lateral curve of the existing S 30 mast is determined with a circle – photo Swedesail

Standard solution saves money

So the only option is a standard solution off the shelf. Gotthardt kindly helps with a construction drawing of the Seldén mast fitting, specifying several different radii. I print out a photo of the template 1:1. Apparently the mast has a radius of 139 mm at the side where the eye plates are mounted. Presumably a particular variant of the usual Seldén eye plates will fit. It just need to be mounted slightly tilted aft. A slight variation of the radius could be compensated by the rubber underlay to avoid electrolysis of the aluminium. So I order the parts for the customer and hope that they do actually fit, as measured at the desk in the office.

The following weekend, I receive the above photo from winter storage. It shows that the fitting sits well to the gold anodised mast. So even a simple and banal thing like ordering a jockey pole and two eye plates is best done in the winter months with sufficient time.