Sign in to follow this  
Tyson0317

What Aluminum Alloy to use for a Spinnaker Pole?

Recommended Posts

A few weeks ago I converted my J/35 to an end-for-end pole setup. I threw this on my crew somewhat last minute (with one practice day and some delivery time) before a 2-leg 65-mile race (Orcas Island RTC). They were apprehensive, but at the end of the race the whole crew told me that this was a good call and jibing (even in 19kt of breeze) was a hell of a lot more comfortable!

I could not get my hands onto a cabon fiber stick, as I originally wanted. However, the local Fisheries did have precisely two 3.5" trigger ends and one mast car - I thought this was a sign from God and after some drilling, was able to change out the ends on my existing pole. In the process however, we lost about 3-4" of overall length, as the dip-pole ends and car had more 'meat' to them. Also, the ends of my pole are quite corroded. The boat has a heater, an ice box, a BBQ and other junk that I like - getting a carbon pole to save weight, seems stupid. As far as I can see the pole is nothing more than an aluminum stick and I am certain that I can get one from Alaskan Metals and order the matching wall thickness, then cut holes for the trip lines and stuff on my own.

Only question is, I do not know what Aluminum Alloy this thing should be. 

Anyone see any issue with me doing this? Am I missing some special "metal blessing" that Forespar puts into their aluminum to charge the prices that they do?

Share this post


Link to post
Share on other sites

For strength, it pretty much doesn't matter what alloy you use as the pole will fail in Euler compression and this is governed by stiffness, all alloys having the same stiffness. For corrosion resistance, you'd like to have something like 5083 or 5086, but that might be a hard find. 6061 is very common and the next choice, probably what Forespar is using. 6063, also very common, third choice but fine for the application. Find an anodized piece if you can, or get it anodized - if you don't it will begin to look bad after a year or so in salt water. 

  • Like 1

Share this post


Link to post
Share on other sites

On our J/36 we find gybing end for end starts to get too exciting at around 25kts of breeze, so that's when we revert to dip-pole gybes.  Don't know what alloy our aluminum pole is, but are thinking of repainting it over the winter - it's 37 years old now.  

Share this post


Link to post
Share on other sites

Almost all extrusions you will find will be 6061-T6 or 6063. 5086/5083 is used for plate but is almost never found as extrusions (not soft enough to extrude in most cases).

 

Share this post


Link to post
Share on other sites

I used 7075-T7  X 100 mm diameter alloy tube for a prodder I made once. Was available and spec matched application.

Share this post


Link to post
Share on other sites

I too have an overloaded J/35, refrigeration, hot water heater, J/40 forepeak option, 35lbs Manson on a roller on the bow, massive stereo, and on and on.  It's more a cruising J than a racer now. and I like it that way.

But I got a carbon pole for one simple reason, it is sooooooo much lighter than any aluminum tube. Endos are so easy with a lighter pole and I don't jibe above 25kts so that's an non issue. 25kts+, either set it on a no jibe or leave it down. 

Share this post


Link to post
Share on other sites

5000 series can be and is extruded commercially, even 2024 and 7075 are. But 6000 series have high formability and are age hardening so they can be hardened after extrusion, therefore the favorite of extruders. 

I would not use 7075 in salt water, it has very poor corrosion resistance. 

Share this post


Link to post
Share on other sites
8 minutes ago, DDW said:

I would not use 7075 in salt water, it has very poor corrosion resistance. 

Anodised that 7075-T7 six year old sprit still looks like new.

Share this post


Link to post
Share on other sites
4 hours ago, DrewR said:

I too have an overloaded J/35, refrigeration, hot water heater, J/40 forepeak option, 35lbs Manson on a roller on the bow, massive stereo, and on and on.  It's more a cruising J than a racer now. and I like it that way.

But I got a carbon pole for one simple reason, it is sooooooo much lighter than any aluminum tube. Endos are so easy with a lighter pole and I don't jibe above 25kts so that's an non issue. 25kts+, either set it on a no jibe or leave it down. 

Moving a carbon pole will be a lot easier for the foredeck guy. 35ft is big for and end for end jibe. Make it as easy on your crew as possible.

APS has Forte carbon blanks for what seems a reasonable price.

Share this post


Link to post
Share on other sites

The carbon pole isn't to save boat weight, it is to make life easier on the bow crew.  We borrowed an aluminum pole for a while this summer and our bow crew breathed a sigh of relief when the carbon pole came back.

Share this post


Link to post
Share on other sites

What is the actual weight difference between carbon & alloy poles?

Share this post


Link to post
Share on other sites
20 minutes ago, SloopJonB said:

What is the actual weight difference between carbon & alloy poles?

On my old C&C 27 we went from the original 11.75' aluminum pole (3"?) to a similar diameter carbon tube - oversized for my application but basketcase matched the lamination schedule to meet the strength requirements.  Changed over from the original cast fittings to Forespar composite ends at the same time.  Weight dropped from 23 pounds to just under 10 pounds.  Foredeck guru looks (even more) like a rockstar now no matter what the jibing conditions.

 

Cheers!

 

  • Like 2

Share this post


Link to post
Share on other sites

A fuckload.  Don't have the old pole anymore so I can't weigh it but its waaaaaaay lighter, or so I'm told since I'm not allowed up there.

Share this post


Link to post
Share on other sites
19 hours ago, jack_sparrow said:

7075-T7

Yikes. Even anodized, one scrape and it's powder time at the scrape. 

You're lucky you got away with it. Good for bikes, tent poles, and airplanes. Not so good around salt water.

Share this post


Link to post
Share on other sites
23 hours ago, CriticalPath said:

On my old C&C 27 we went from the original 11.75' aluminum pole (3"?) to a similar diameter carbon tube - oversized for my application but basketcase matched the lamination schedule to meet the strength requirements.  Changed over from the original cast fittings to Forespar composite ends at the same time.  Weight dropped from 23 pounds to just under 10 pounds.  Foredeck guru looks (even more) like a rockstar now no matter what the jibing conditions.

 

Cheers!

 

This, and it wasn't really that hi tech of a build.  

  • Like 1

Share this post


Link to post
Share on other sites
On 11/14/2018 at 8:39 AM, Zonker said:

Yikes. Even anodized, one scrape and it's powder time at the scrape. 

You're lucky you got away with it. Good for bikes, tent poles, and airplanes. Not so good around salt water.

In a location that doesn't get knocked around and I anodised post cutting and drilling. I was more worried about lateral loads a bob stay can't resist and it turning into an expensive licorice stick.

Share this post


Link to post
Share on other sites

I have made up a couple of poles, and after being frustrated with the cost looked for un-anodized tubing. (https://www.globaltecheng.com/ProductCart/pc/3-5-14-Gauge-Aluminum-Tubing-28p53.htm )  I have enough tubing in my garage now for my next 3 poles.  I bought 4x20' lengths because the shipping was about the same as for 1.  I found that with Moeller zinc chromate spray primer, good isolating goo at fasteners, and Rustoleum redone every 5-7 years, I am quite happy.  Mine are only 10.5' and 2.5", so my weight savings are not worth the cost of carbon.  I do like the Forespar ends for weight, but I do not like how the dyneema trigger lines eventually pull out of the pole ends.  That is a bitch to repair while racing.

On a C&C 35 I've spent some time on, a carbon pole made the foredecker very happy, relative to the Aluminum version.

Share this post


Link to post
Share on other sites

no need to anodise but nice if you like that look. My ali pole is 20 years old and au natural, its doing just fine. End for end on a 35 is piss easy in breeze if you use lazys and have good trimmers.

Share this post


Link to post
Share on other sites
17 hours ago, toad said:

no need to anodise but nice if you like that look. My ali pole is 20 years old and au natural, its doing just fine. End for end on a 35 is piss easy in breeze if you use lazys and have good trimmers.

As mentioned above, lazy guys/double sheets and guys,  are the answer as soon as the breeze is up.  Carbon all the way!  

Share this post


Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now
Sign in to follow this