Converting keel stepped mast to deck stepped

Why wouldn't you weld the tabernacle to the deck plate (with doubler or thicker section as necessary)?

Every bolt hole is a possible leak. Every bolted fitting to a steel deck is a possible rust area waiting to happen underneath.

Unless there are really strong engineering reasons for NOT welding, its certainly what I plan on doing.

PDW

 

PAR, I can only repeat what I said before. One of the advantages of a metal hull is that it can be made into a homogenuous, tight structure. Every hole in it is a potential source for leaks, if not now than sometime in the future. If I can have a watertight deck, I want one. The same for as much space available below as possible. Others might choose a keel stepped mast for other reasons. To each his own.
Walter

 

Mike, that's reassuring, tanks a lot! It seems the whole project comes back to the mast I have.

I am wondering the same as Peter: Why would you use bolts instead of a welded flange? Not much sense in welding shut one big hole only to put in many smaller ones?

Actually there is the issue of a pilot house which is highest on the wishlist. No need to shoot me for that now, I will come back to that later.

Walter

 

Sounds like fun. Please let me know what you come up with regarding the pilothouse!

Me neither, they are really in the way. But that's how they are and if I'm doing something with them, that will be for much later.

It's a Dickinson Pacific (http://www.dickinsonmarine.com/stoves.php). Tell you what: You come and get it for free. All you have to do is take the boat back home and make the mods I want - I give you a list

That's the plan. For now I want to know what the conversion will involve and it seems that it can be done with a reasonable constructed tabernacle if the mast I have is up to it.
Thanks everybody for all the input!
Walter

 

Northman...a tabernacle does nothing to address your inline rigging problem. You must modify the present rigging geometry and use fore and aft lowers. These lowers initiate mast prebend , absorb the compression load of main boom and spi pole and keep the bottom section of the spar in column . .

In addition, from your interior picture, you have no ring frame or bulkhead at mast penetration and you have a huge cut out opening hatch aft of the mast partners.

These issues must be addressed when you move mast compression to the cabin top with a deck step rig.

 

Michael, thank you for your input. Along with several other posters I am not really convinced that the inline rig actually presents a problem; neither that I need lowers.

I don't need a ring frame when I have a compression post. With regard to the hatch I think you let the light in picture 1 fool you. As you can see in picture 3 the hatch opening is about 40 x 40 cm - hardly what one will call "huge".

Walter

 

Run your thoughts on deck stepped masts by a mast builder. His eyes will grow when you inform him about inline rigging.

You should also consider strategies to remove compression from the mast. The easiest and cheapest way is to reduce halyard loads . A " Two to one" main halyard and a halyard lock or Pro furl type roller headstay are effective.

Be aware of the boom vangs load on the mast foot. Moving the vang from the mast butt to the deck is effective. Moving the spi pole butt off the mast and onto the deck is effective.

 

Michael, im not sure how a profurl furler reduces mast compression,all the ones ive installed are of the double swivel type that use the masts own halyard which of course imparts compression load on the mast. There are quite a few that do take the loading off the mast by having their own halyard which comes back down the forestay and cleats off at the bottom. I have a very old Famet furler of this type on one of my boats and like it a lot for its simplicity. Maybe Profurl have one of this type that i havnt seen. I would certainly be easy on a steel boat to rig the vang to the deck as you suggest. An assym could get rid of the pole altogether and make for easier cruising.
Steve.

 

Peter, Walter

Depends what you make the tabernacle from. It can be alloy, stainless steel, glavanised , high tensile or plain painted mild steel.

I just like bolts because they are predictable and I'm usually liable . But bedding/sealing compounds are really good these days.

A bolted tabernacle can be lifted off with the mast but it can be welded for sure if you want.

 

Funny, I've got 5 different rig plans for my hull, all done by the designer. 4 of them have inline rigging. The one that doesn't is a bugeye rig with a heavily raked mast.

Walter's original design is what it is. The mast hasn't fallen down before (as far as has been said anyway). Changing the rigging geometry (as opposed maybe to the mast section) is work without a reason.

PDW

 

Bolts might be predictable but so is around a metre of 3mm fillet weld (assuming approx 300mm dia tabernacle base ) Would you bolt down mooring bitts, lifeline bases and the like?

OK, so really it's builder's choice as to how to do it, thanks for confirming that. I think I'll weld mine down. If there is no hole, there is no possible leak. Modern sealing compounds are excellent but why bother unless you have to? If someone in the future wants to alter the rig, lots of luck and I hope you're good with an angle grinder....

PDW

 

Thanks but I'd rather you delivered it and I'll build your tabernacle for you

Not sure what I'm doing about a small pilot house as yet. Maybe nothing. I've a few things to think about and that's one of them. As the decision doesn't affect a lot of the other work I'll let that one sit awhile. Big issue is the mast will come through the middle of the pilot house and the extra height might force me to either use a deck (cabintop) stepped mast or a keel stepped one because an effective tabernacle might end up a bit too high. I have to write to Tom and ask him some rig questions soon, might add it to the list. What's one more stupid question after all....

PDW

 

Profurl for small craft also runs the halyard down the forstay then uses the tail as the roller line.

Not practical to eliminate the spipole on any sail boat. For ocean work poled out foresails are always preferred over asymmetrics.

 

A better reason than most
Thank you for good advice (as always)!

 

Be carefull, I might just show up some day ...

Well, that's what you pay a real designer for, isn't it? Let me know what you come up with!
Walter