Is there a specific grade of aluminium for the beams?

Hi Dave,

Nothing in the building restrictions that I can see regarding grade of alloy. The following is the only applicable part I can see that effects beam materials.

"The main beam and rear beam shall each be of straight aluminium alloy of constant section along its length. Holes may be drilled in the beams for fastenings only. Holes remaining after the removal of redundant fittings are permitted.
6.2
The main and rear beam shall be; a rectangular hollow section 50 mm plus or minus 1 mm by 39 mm plus or minus 1 mm by minimum 3 mm wall. Beam edges may be rounded to a maximum of 2 mm radius."

From my experience this size only leaves Mossies with a choice of a standard section from Capral, available at most alloy fabricators/sellers around the country. Though it does come in a choice? of internal corners rounded or not, rounded internal corners is preferrable, in particular if you are not bolting beams right through.

Have you found a alternative in this size?

I have just bought beams for myself from capral and cost $72 for a 6.5M lenght 50.8 x 39.2 x 3mm untreated and pick up. it has internal radius.

Matt

Good price Matt, I expected it to be more than that for a full length

Does the association carry the beams ?
(Reason I ask is I need 2new beams for 1740 and I also want a new mast aswell, killing two birds here )

Mast batch should of been ordered (ill follow it up)
Yes the assoc do stock beams (i dont think we have any in stock. If not will be ordered with masts)

Matt

Was not sure if there were different grades of alloy as there is with stainless steel. Good tip on the internal round, I would not have thought of that. At that price I will be re-beaming next weekend. Thanks for the replies.

Hi Dave,

What boat are you re beaming? I thought we did all 3 Mossies I got from Port Lincoln 1747,1749 & 1760, remember buying a number of lengths of beam section from local alloy supplier, even had some left over, in fact sold the last left over beam to Matt a while back.

Hi Gary
Re-beaming 1749 "BITE ME". Found a small hairline crack 5mm inboard side of where the tie bolts to the main beam. Small amount of corrosion looks like the cause.

The joy of getting older can't remember stuff , obviously didn't re beam 1749

hmmm thats where daniels cracked too, put a 20x40x3mm plate/ washer on the strap when bolting on to the beam.

Matt

Agree with the mate about aluminium cross beams .

Just out of interest in regard to the mast sections from the association, are they anodised? or natural?

Cheers

anodised

Hey Matt,

I'm in the process of replacing the rear beam on 1747. (PS. for Gary: 1747 rear beam was definitely not replaced!)

Does the Capral section you bought have an external radius too? I've got Nic's boat at my place and his seems to have a small radius on the outer edges also which is a nice detail. ( I think PhilWS beamed his so I would assume the assoc supplied these?)

Is there assoc. stock available and are they anodized? Either way I need to get some beams over the next few weeks.

Cheers
Doug

Hi Doug,

No need to rub it in, I thought we had established the fact I don't have a memory .

The Capral section doesn't have a radius on outside corners. Phil WS does this himself before he gets them anodised, to supply on the boats he sells (which are not sold by the association).

On the beams I did replace, 1760 and . I did the radius myself, it's not that difficult, I did a lot of it with sandpaper, before anodising. Getting them anodised is not difficult in the Eastern Suburbs (mine where done around Cheltenham Road I think?) as long as you are not in a rush and can wait till they have enough for a bath lot.

Contact Phillip WS direct to check if VMCA has any beams For Sale and if they are anodised.

Hi Doug, as Gary said, I do also radius the edge with a fine flapper disc on grinder then go with the grain with scotch brute pad to clean all grease and make it smooth ready for anodizing, I do have a section at home I could sell you a beam or make one up for u
Matt

Also I can get it anodized for you about$60

Thanks gents

2 questions .....

1/
Is it within the rules to "radius" the beams ?
I know there's a limit on the deck/hull radius, so logic would suggest ...


2/
Wouldn't it be best to actually fit the beams to the boat and also the associated hardware (IE: trampoline, traveler bar, dolphin striker etc etc)
And then strip it all off and THEN get it anadosied ????

Cant see the sense in drilling holes and exposing raw alloy after the anadosing

Reason I ask is.....
1182 has an anodised rear beam and a 'painted' front beam, the rear looks a treat until you remove a component (in my case the traveler bar), the corrosion around the holes that were obviously drilled post anodising is a concern, and yet the corrosion on the pained front beam is probably less in comparision
(more on this comming to Shy's thread soon).......

Yes there is a rule on radius of the beams. Rule 6.2.
I would suggest it is a good idea for everyone to read through the rules at some stage. If you read the rules and check your own boat it saves the embarrasment when it doesnt measure at a regatta.

http://www.theracingcat.com/uploads/Mosquito_BRR.pdf