Measuring point for mastband distance

posting disabled

Moderator: forumadmin

Postby Guest » Sat Feb 04, 2006 12:21 pm

i haqve just repainted my mast and can"t work out from where to measure the distance for the mastband If I measure fromj the base of the mast I end up short Does anyone know?



Postby Guest » Sun Feb 05, 2006 1:35 pm

I'll give it a shot, defering to the class measurer if there are any conflicts.

Refer to the Equipment Rules of Sailing available on the ISAF website at
The "Lower Limit Mark" is defined as:
B.7.1 "When the sail is set on the boom, the extention of the upper edge of the spar [boom] shall intersect the mast spar above the lower limit mark, with the boom on the mast spar centreplane and at 90deg to the mast spar."

The bottom edge of the "upper Limit Mark" should be 9144mm above the top edge of the "Lower limit mark".

Our class rules seem to call the "Lower Limit Mark" the "Boom Spar Band", and the "Upper Limit Mark" the Upper Mast Spar Band", but I think they are equivilent and must be measured by the ERS definitions.

Be careful not to use electrical tape to replace the bands. It will deteriorate with UV and become soft and move around in the sun. The best material that I have found is to ask a vinyl sign cutter for a couple of pieces of black sign vinyl. This stuff works great and is very UV and heat resistant.

Postby Guest » Sun Feb 05, 2006 8:20 pm

Bob thanks for your help. If I take it from the lower limit mark (which I understand to be a fraction lower than the top of the boom)I come out about a meter over the top of the mast. Although this works for me others might disagree.

I think the reading must be taken from the mast datum point. ERS F7.2. says the upper point height is the distance between the mast datum point and the upper point. The problem is that ERS F.5.1 says the mast datum point is specified in the class rules and I can't see any reference to this in the class rules.

Does anyone know how to measure the mast datum point?


Postby Guest » Sun Feb 05, 2006 11:40 pm


Maybe your mast is short.

Seriously, you should probably call someone at Hall Spars for the measurement procedure.

Return to Archived Racing Tools & Techniques

Who is online

Users browsing this forum: No registered users and 1 guest