[Public-List] cabin top traveller

[Andrew Johns]

The primary reason for a cabin top mounted traveler is to allow for a
decent bimini and dodger setup that can be used while sailing.
Additionally, it allows for extra room in the cockpit.

We have had a cabin top mounted traveler on #104 since 2002.  We have a
Garhauer traveler mounted on teak riser blocks over the rear of the sea
hood. In my experience, the masonite cored deck on the earlier boats is
plenty strong enough for a traveler.  No signs of distortion or stress
cracking.

The purchase on the mainsheet was increased to 6:1 in our setup.
Occasionally we use the cabin top winch to help sheet in when close-hauled.

A few things to keep in mind the force on the boom is not a single point
load, it's applied over the length of the boom with the load reducing as
you move farther out (providing you don't have a loose foot main).  Moving
the attachment point from the end to the middle would not double the stress
in the boom.  It would double the stress in the mainsheet but not the boom.

Andrew
Ecola #104


On Fri, Aug 16, 2019 at 8:52 AM Don Campbell via Public-List <
public-list at lists.alberg30.org> wrote:

> Hi Walter:
>      This is about your comment to go to a cabin top traveller. Really
> consider the forces you are changing when you think about doing that.
> Firstly: you change the moment of the force on the boom from now 14’6” to
> about half of that. That means you will double all the other force
> requirements for the track and blocks, gooseneck,  and boom. So if you are
> now happy with the designed 4:1 on the main , you will have to go to at
> least 8:1 for the same pull on the sheet.  It will also mean you change the
> forces on the boom, mast track,  and  the sail itself. In fact getting a
> method to hold the connection to the boom for the mainsheet blocks without
> compromising boom strength and still able to withstand the extra forces is
> a real challenge. When a boom breaks in half, it is not a very pretty
> situation with sail and boom end flapping around your head. Secondly: The
> cabin top has not been designed to take the upward force that this proposed
> change will incur. While the builders have not known what fiberglass would
> do, so they overbuilt things, changing the structural component to try to
> do this change was not a part of the design or serendipity that we have
> enjoyed with a strong hull (which is different from the cabin top and
> deck). Thirdly: you will change sail shape and have a leech that will
> always be open because you will lose control of the end of the boom, This
> will offer more opportunity for a luffing leech and that is not an easy
> sail for power.  Lastly, you will have made the boat not class legal and so
> it can never be sold to anyone who might want to race her.
>
>     I have no idea why one would want to change the traveller position,
> but if it is because the original equipment is slow, sticky or just
> awkward, then consider changing to a new track system and leave it where it
> is now. Hardware manufacturers do a really good job now of making things so
> they work in all conditions, and I know we have Albergs with new gear on
> them. I put Harken on #528 twenty  years ago now and I still like the
> system. I know others who have used Garhauer and they like that too. Really
> consider the change at boom end. I am also sure that if Carl were alive
> today and designing boats, or even commenting on refits, he would be using
> today’s hardware because it is functional , well built and safe.
> Don
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