With the Widget I am assembling at the moment , depending on the jib attachment I use, the height of the jib boom will be affected. I notice on the Lintels that the jib boom is a little higher than the main boom. Indeed the advent of raised foredecks and scooped or skiff style rear decks makes if difficult at times to get the two booms at the same height. To what extent is this critical. In other words is there a disadvantage if the jib feeds the air onto the main at a slightly higher point than normal ?
Hi This is something that I have looked and even gone to the trouble of photographing the better performing boats I sail against to see if there is any pattern.
Stari
ng with the main sail: The majority of boats have the bottom of the main boom at the same level as the rear of the foredeck (most Cockatoos, Widgets and Topikas). This means that the foot of the main sail is about 25mm above the rear of the fore deck. There are some exceptions to this and I and one or two others prefer to have the top of the main boom level with or just belowthe top of the foredeck, this means the sail foot is slightly above the foredeck. One particularly good Widget skipper has used a plain bearing gooseneck which is cut down to achieve this. I design and build my own boats and use a deeper aft deck recess than is usual. The exception seems to be the Lintels which have more stability than other designs and seem to carry the main boom slightly higher ( last photo I have is May 2008).
The position of the jib pivot is obviously restricted by the design. I tend to go as low as possible but with a requirement of a straight boom the problem is that the foreward end of the generally fowls the deck before the deck pivot to boom hieght becomes a problem. I now break the sheerline roughly at the jib pivot location and continue the fore deck horizontally to the bow. I have not noticed a marked increase in diving due to the small loss of reserve buoyancy.
To answer your question I'm sure that the sails would work best if they are aligned but it is a compromise. The main problem preventing this is the relative hieghts of the fore and aft deck and the need to improve stability by lowering the rig as far as possible. Also with the IOM there is not a lot of room between the top of the jib and its attachment point on the mast and this limits the amount the main can be lowered relative to the jib.
