Replace baba 30 wood mast with 1983 catalina 30 mast?

[dfw_sailor]

Have a friend who has just bought a 70's baba 30.

He plans to sail the Caribbean and off Spain in 3 years. 

Baba is in rough shape,  suffered from rain leaks with rotting shelves and sub floor although the teak is mostly in very good shape.  Also has some cabin core rot, but that is only a few weekends of work for him.  He is very good woodworker so interior won't take him too long to fix (after all leaks,  through decks redone, including chain plate tournaments).  It will take him about 2 years to repair, but fits his plan and skills  perfectly.

He had a lightly used catalina 30 mast which is 1 foot taller. In this case the mainsail is missing, and I can give him a very good condition siedlmann 299 main correct for the Catalina mast and has the same long boom foot. Is 220 sqft compared to baba 30 design which is 200 sqft.

Assuming new standing and running rigging,  would a cat 30 mast be ok on a baba 30?

 

[SemiSalt]

A big factor in mast design is the (I forget the tetminology) inertia that resists rolling, i.e. how hard or easy is it for the boat to roll in response to a gust. This depends a lot on weight and draft. 

 

[El Borracho]

Might be a good swap. Less weight aloft (presumably) is always good for both rolling in a seaway and upwind speed. Spreader length could be an issue. Too short could mean weaker. Too long looks goofy and slow upwind if headsail overlaps.

Does the aluminum mast have about the same cross-section as the wood?

Sailboatdata.com thinks the Baba 30 mainsail hoist (E) is 39 feet vs. 35 for the Catalina 30. FWIW.

 

[GH41]

You said he bought it? Are you sure?  

 

[dfw_sailor]

I believe so.

 

[dfw_sailor]

Baba 30 mainsail hoist (E) is 39 feet vs. 35 for the Catalina 30. FWIW.

Hmmm, I am seeing 35ft for both , for P, max hoist to top of boom.

 

[El Borracho]

My bad. 

 

[SloopJonB]

A big factor in mast design is the (I forget the tetminology) inertia that resists rolling, i.e. how hard or easy is it for the boat to roll in response to a gust. This depends a lot on weight and draft. 

Moment

 

[dfw_sailor]

My bad. 

Appreciate the effort though.  And your other comments,  thanks. 

 

[SemiSalt]

Moment

On reflection, when the designer finishes his calculations, the result is a number called, IIRC, the moment of inertia which is a calculated from the cross section of the extrusion/spar. It's the number they would use to pick the extrusion for a new design out of the catalog. If you can find the data for the two masts you can see if they are comparable.  This does assume the rig has the same number of spreaders, length of spreaders, same staying  plan, etc. You can get away with a skinnier mast if you use more wire, or simplify the staying if you use a stouter mast.

 

[Morello]

I believe that Bob Perry is the designer of the Baba 30. I would call him and pay his consultation fee.

 

[sculpin]

Overcomplicating things greatly.  If he has both masts, weigh them.  Similar weight, similar boat performance with regards to stability.

I'd look to get as close as possible to the original rig in terms of spreader position and length.

Are they both deck stepped rigs?  Both are masthead jib rigs, so OK there, but for a Baba 30 isn't there a cutter rig option?  That would complicate things... 

 

[Diarmuid]

My bad. 

Cat 30s Mk1-3 came in standard & tall mast versions (P= 35' and 37', respectively.)

 

[dfw_sailor]

Overcomplicating things greatly.  If he has both masts, weigh them.  Similar weight, similar boat performance with regards to stability.

I'd look to get as close as possible to the original rig in terms of spreader position and length.

Are they both deck stepped rigs?  Both are masthead jib rigs, so OK there, but for a Baba 30 isn't there a cutter rig option?  That would complicate things... 

Both stepped,  the baba carries a jib and a staysail. Plus intermediaries for the staysail mast position,  although apparently RP went a bit cool on the value of those over time.

 

[dfw_sailor]

I believe that Bob Perry is the designer of the Baba 30. I would call him and pay his consultation fee.

Yup considering that method.  Going to ask on the owner's forum first. Is somewhat active. 

 

[SASSAFRASS]

1hr of time with a NA on the clock and you will know for sure and sleep well.  BP will probably even set you up with a nice sailplan dwg.

 

[Panoramix]

According to sailboat data, a Baba 30 is heavier than a Catalina 30 so I would definitely find a way to check the new mast as heavier boats tend to be stiffer and thus harder on their mast. IMHO, the way forward is to to either hire a  naval architect / engineer or at the very least compare the inertia of the new section to the old one as explained by @SemiSalt above. 

 

[SloopJonB]

1hr of time with a NA on the clock and you will know for sure and sleep well.  BP will probably even set you up with a nice sailplan dwg.

^^^ This.

This is a classic situation where one needs to understand the difference between economizing and cheaping out.

 

[El Borracho]

Be interesting to hear what a professional says. However, given the same outside dimensions any reasonable aluminum tube is far stiffer than any wooden pole. I think stiffness is the controlling criteria. Plus aluminum must be far lighter for which the only downside is  perhaps slightly increased rolling when not sailing.

The Moment of Inertia of a meaty wooden pole is much greater than the comparably frail aluminum tube. However the Moment of Elasticity of aluminum more than compensates no matter what the varnish sniffers over on Wooden Boat Forum opine. But I only play an engineer on TV.