Soon another junk in France ! That's good news, go ahead Jacques ! :)

Bonsoir Jacques

The mast step should be made of plywood and epoxy to spred the load of the pylonning mast (shoppy sea) to the hull. 

The tube is more an alternative or a complement to the reinforcement at deck level.

The tube goes from the mast step to the deck and above; as it is on a Laser. It is an elegant way to build a stuck. It prevent any water ingress at deck level. It uses the two plywood vertical reinforcements under the forward berth to spred the efforts. 

Of course, a water drain should be available at the mast step. 

I agree that there is a risk of corosion but normally the aluminium tube should not be in contact with water and even less with salty water. This tube should be in a dry zone protected by the waterproff mast colar, at the stuck level. Of course a drain should be installed at the bottom of the tube to let any water or condensation out.

As both tubes, the mast and the partner are in aluminium, the risk of electrolysis should be minimal.

Eric

PS : My knowledge is academic and ingeneering! I don't have any experience hands on in this domain !

Bonjour

If you look, on the photo, inside of the "window" at the bottom of the lamp post, there is already a sleeve welded inside the tube to reinforce it. 

Eric

For my 24m² sail, I use a 3 part halyard, with no efforts.  It's already a very long halyard ! You can use a winch for the last panels if it's too heavy.

For the upper sheeting, I followed Arne's advice with more anti-twist : Malena upper sheeting fig 2 . You can see that in the beginning of this video https://youtu.be/pLmDwkylE78?si=FJrRqv7ZyE6stvPB&t=21

It reduces chafe on the sail if you use a large webbing for the bottom of the mast lift. I used a seatbelt.

With an aluminium tube as a partner to the mast step, I'd be afraid of corrosion between the mast and the "partner tube", it could be difficult to lift the mast after a few years.  A plywood mast step glued to the hull and reinforcement with plywood at the partner will be enough for strength.

I hope I could show you my boat soon !

Anonymous wrote:

Anonymous wrote:

Bonjour Jacques

In terms of mecanical efforts, the more burry (height between the mast step and the stuck) the best. A rule of thumb is to have a bury of at least 10% of the mast height. 

In your drawing,  the mast step is positionned quite high in regard to the bottom of the hull. 

I would rather put it as low as possible. 

There are at least two different options. One would be to cut the longitudinal plywood reenforcement to give way to the mast, the other would be to move the mast laterally a few centimeters to position the mast against the longitudinal reinforcement. It could even be possible to build the mast step as a tube (as on the laser) that would be glassed to both longitudinal and transversal reinforcement. 

In this case, you would have at the lower part,against the hull, a few glassed layers of plywould to flatten the hull shape and provide a horizontal support to the mast. 

Eric

Ok , i choose second option ,i'm making a new draft