IMCAI TECHNICAL RESPONSE
Herewith the comments of a subsection of the IMCAI membership as prepared by
our chief measurer, Brain Adley. Please note that any change will require
the appropriate votes of the National Associations, that the IMCAI does not
plan (because of Exams and other absenses) to hold an EGM to consider this
proposal until Summer 2005 (and likely in late June or early July) and until
we do the IMCAI will be unable to approve this change. Please advise if an
earlier approval is required, and please specify what the constitution of
the IMCA requires in terms of procedure and timing so that we can take
appropriate steps in the time required.
IMCAI comments on the UK Mirror Association Alloy Spars and Bermuda Rig proposal
April 26 th 2005
The following comments come from members of the International Mirror Class Association of Ireland (IMCAI); its committee members, measurers and builders were solicited for comments. It is a matter for the members of IMCAI at a general meeting (which the IMCAI plans to hold before Sweden) to determine the reaction to any proposal before the IMCA and such views may differ from the views expressed here, it is intended that, following receipt of the final proposal from the UK Association (and after consideration of the issues contained in this memo), the IMCAI Committee would recommend the proposal to its members. The collated responses of this technical interest group (IRL-tig) received to date follow:
- The IRL-tig welcomes the UK Mirror Association’s work on an alternative Alloy Bermuda rig proposal for the Mirror class.
- The mismatch between the increasing rigging tension on current Mirrors and the wooden spars is widely recognised. In addition, given the wide disparity in weights and densities of wood used in existing wooden gaffs, they are hardly “one design” as it is. The alloy spars should be more one design.
- The problems with gaff breakages and the cost of replacement are well known. As is the difference in the wood used and thus the weight, increasing the risk of injury.
- There was wide support for an improved Mirror rig, but only in the context of keeping the existing rig as a viable option.
- The proposal for an alloy boom did not invoke any specific comment, and is supported by the majority of IMCAI commentators.
However, there were a number of comments relating to the mast proposal that may be of interest:
- Generally it was felt that the new Trident designed mast could (and should) be improved upon. If we are going to change the mast material why not try to improve the design (in terms of simplicity, ease of use, durability and reliability) rather than just replace wood with alloy. Specific comments on the prototypes of this mast included:
- Fittings/attachments of poor design and with more parts than seemed necessary. This has resulted in fittings falling off, being lost and defeating some of the purpose behind the new mast.
- Does not improve on what many consider to be an overcomplicated rig with lots of opportunity to make mistakes.
- The external track looks awkward and the mast appears too stiff.
- A mast that separates and fits into the boat is considered vital for the following reasons:
- Transportation is much easier as the mast breaks into two parts.
- Mirrors are best stored with the mast down and a flat cover. This keeps the water out and is especially important, as there is no drain hole.
- It was felt that it was not practical to allow individual manufacture’s to come up with there own multi-section designs. However, it was considered essential that a professional mast design experts views be sought, so that the new rig uses best available design and materials while remaining
- Simple and uncomplicated, so meets needs of younger sailors and beginners
- Robust and durable, as few parts as possible (fewer to lose and break)
- One design and inexpensive, perhaps readily available from multiple sources (for cost and supply reasons)
- Use existing materials and fittings (readily available and suitable for purpose) while also looking to the future.
- It was also felt that the strengthening of the mast step might need to be considered with provision for drainage (through hull) if the new mast would generally be left up for storage.
In summary the feedback from the IRL-tig is:
1) An alloy one-design mast should be proposed as an alternative to the current rig for reasons of cost, reliability and safety.
2) A design should be sought from a professional mast builder with the following design goals:
- Two piece design for ease of transportation
- Design based around readily available D section alloy preferably with a tapered top to reduce windage and improve aesthetics. However, righting forces from a capsize need to be taken into account.
- Easy mast assembly with no possibility of track misalignment leading to snagging of sails
- Preference for an internal sail track
- Improvements should be made to the rigging to make it simpler, more reliable and quicker to rig/de-rig than the current setup.
- Compatibility with existing sails
- Standard components and mast cross-section, to prevent possible monopolies
Other miscellaneous comments that may be of interest are:
- The possibility of running the halyards inside the mast
- The discussion on storing boats with the mast up, brought up the subject of drain holes and the need to keep water out of the boat while on the hard. Advocates felt that this might be a good idea anyway irrespective of any rig changes.