Stumping Squid

[Jimmy Rudd]

Squid work is coming along nicely, its now time to stump and I need some advice.
I have some large diameter carbon tube for the main stump, and two lengths of smaller diameter for the arms.
My plan is to cut the stump to the length so it goes from floor to gooseneck, maximising mast height. Cut a rectangle slot vertically out of the bottom of the stump to slot over the box the mast currently sits on(seen in photo, tunnel has since been removed), then fix this to the floor with some carbon. The arms would then be put on going from stump to shroud points.
My main concern is the bottom of the stump and what to do with it? A) As described above, slot in the tube over the old mast foot area? Or B) Putting a mast foot on the bottom of the stump, and simply put that in the current mast base?
Any advice or thoughts appreciated on this? and the whole stumping thing?
Thanks guys

[scorpion_1925]

Could you take the current box out so you can mount it directly to the bottom of the hull?

[RobinJones]

Directly to the bottom of the hull would be best, but would involve some proper boat surgery to attach it there.

Mine terminates at the cockpit floor in a similar way to what you're suggesting, and is now stiff. I wouldn't want to use the existing mast base, as the kicker load (as this will presumably be anchored on the stump) will be putting a lot of force directly into that fitting, and if it were to break, it would be a pain to replace. Likewise, you'll need a very strong joint between the floor and the vertical stump tube: mine is a piece of 20mm thick Utile (hardwood) with a 55mm hole cut in the middle. this was glued to the floor of the boat, then 2 larger layers of carbon placed over the top and vac bagged down to hold it well. The stump then just sat in the 55mm hole in the utile, and was filleted in.

[Phil Alderson]

Do you know what is inside the composite part of the current mast step? If it is solid then you could slot your tube and fit over the top, then bond to it with lots of 45's.
I have had to chop rotten wood out of every old glass boat I have ever had to fix so I would use either some HD foam or G10 to spread the load if you could not keep the load transfer through the fibers.

You also need to think what you want the side supports to be doing. Structurally the joints at the boat and stump they won't be much stiffer than pinned joints so you need to think about the angle of the strmp and what the rig tension is going to do. Also the angle of the stump affects what happens with the kicker when the boom goes out.
 

[kerrgreg]

Mines like this:



so not slotted but bonded in 4 directions everything meets flush and then is bogged into place followed by bi-ax tape everwhere i can get it.

This is designed to be the same sort of setup with the gooseneck and kicker attaching to the stump, the top of the stump will have some wires coming down to the shroud base to help with gooseneck loading and the bow section has been stepped up to provide additional bonding surface. Hopefully its strong enough. (tube is 75mm dia - yep! )

[Tim Noyce]

I put in a new mast step when I rebuilt 2648 a few years ago. It did have a gooseneck high stump, but I found that it was flexing too much under kicker loads as it was unsupported and I didn't really want to put in additional tubes to support it. Also, I was aware that the stump was made of a very heavy piece of tube which seemed to not be attached to the floor very well. The mast was also a classic Angel 600 job and the ally sleeve was expanding and causing the laminate to crack (and was also incredibly heavy at the sleeved bit. )

Long story short... I replaced the stump with a shorter 'deck stepped' arrangement, and then extended the mast.

Picture attached of what my stump looked like when I put it in. From memory, I placed a few layers of weave under where the mast was to sit to form a plate to spread the load, and then I tied the stump in to the UD's which were spread across the floor and also the foredeck support bulkheads in all directions. I had also replaced a large proportion of the floor under the foredeck, so when that was off I also reinforced the main bulkhead underneath the stump.

As Phil has mentioned, it's totally worth thinking about the angle of the stump in relation to the rig before you put it in as it's a lot better if it's in line. I got a mast foot machined which fits together really nicely, but it does have it's drawbacks. In hindsight, although I set stump in an angled position, it's not angled far enough back. The mast foot fits so well that it doesn't allow the rig to pivot back and so when you pull the rig tension on, it actually ends up pulling it straight in relation to the stump (which in turn actually has the effect of putting a lot of pre bend into the lower mast) which isn't very flash for powering the rig up. To counteract this, I then have to put a metric sh!t tonne of tension on the lowers to pull the mast straight enough.

I plan to machine a new mast fitting to sit on the stump which is angled in relation to the stump so that there is no bend induced by the stump.

[Jimmy Rudd]

Thank you all for your help and advice. I think stumping squid may take too long this year if I still want to make it to nationals, so.....
I am thinking of extending the mast and having a deck stepped mast as per original. I don't need to extend the mast all that much, I think its about 500mm, so planned to use a carbon tube of the same OD as the mast to the length of the extension, then put a tube with the same OD as the ID of the mast inside the mast and the extension. If I put the inner tube from the bottom of the extension and then inside the mast by the same length, so 500mm extension and 1000mm inner sleeve, bond them together, will this be enough strength? and not simply explode as soon as I pull rig tension or kicker on.
Any advice or ideas or mast extending appreciated.

Cheers

[roland_trim]

Depends entirely on what your tubes are made of.

[AmusingOutrigger]

I think I have the bottom 500mm of a rs800 mast from before my boat was stumped if you are looking for bits of mast.

Can dig it out if you want to know the diameter and length?

[kerrgreg]

I think I have the bottom 500mm of a rs800 mast from before my boat was stumped if you are looking for bits of mast.

Can dig it out if you want to know the diameter and length?

Think I might have that? - Jimmy is welcome to it if its of use, Im sure i can get it up to him.

[Jimmy Rudd]

Depends entirely on what your tubes are made of.

Should have said carbon tubes......

As for the bottom of an 800 mast, that sounds perfect. Kerrgreg, I'll message you.

[flatbackcaper]

glad unused bits of eva being put to good use, happy carboning.

[Jimmy Rudd]

I think I have the bottom 500mm of a rs800 mast from before my boat was stumped if you are looking for bits of mast.

Can dig it out if you want to know the diameter and length?

Just tried to send a personal message, but not sure it has worked. Would be really interested in the bottom the 800 mast if you have it. If my message hasn't come through, can you PM me?
Cheers

[JP233]

I think I have the bottom 500mm of a rs800 mast from before my boat was stumped if you are looking for bits of mast.

Can dig it out if you want to know the diameter and length?

Just tried to send a personal message, but not sure it has worked. Would be really interested in the bottom the 800 mast if you have it. If my message hasn't come through, can you PM me?
Cheers

Happy to be transport from south to midlands for it if I can be of any use.

[AmusingOutrigger]

Have found the rs800 mast bit, it is longer than I remembered it being.

It is in two sections with a sleeved sliding top section, the sizes are as below.

Total length : 101cm

Bottom section length : 82cm

ID : 56mm

OD : 60mm

PM me if you are interested.