Flagpoles for Princess 26 Mast?

[wasserboot]

Hello, i have the opportunity to get 2 tapered Aluminium Poles. 
They are 8 metres Long the diametre is from 120mm to 70mm .
Weight is 27 kg  (sorry i am living in the metric part of the world).

In imperial it should be about 28 feet long and diameter is from 4 7/10"   to  2 8/10"  weight is 59#
.
Will they be good enough for a Princess 26? Or are they too heavy?
What do you think is best suited for the boat (no carbon - too expensive) ?
 

I do not know what kind of aluminium-alloy it is...The orign use was for street Lanterns or Flagpoles

[PAR]

Most tapered aluminum flag poles are spun aluminum and inherently weaker than aluminum tubing. It should be a simple thing to compare the respective weights of the designed masts, to the flag poles.

[wasserboot]

Thank you, of course i do not want a weak mast. So i will not buy this Flagpoles.
Unfortunately there is no expected weight in the spar plans. 
​But there are two mast versions. One Mast completely made from Wood.
And another is made from a bottom part of Aluminium Tube  and a upper part of Wood or fiberglass. So is it right, that this bottom Aluminium Tube is untapered?
The plans are not so precise or may be  my english is too bad to understand it right.
In the Spar plan is written:"lower section of mainmast to be 4"x 0.125" 6061 T6 Aluminium" So i guess it is untapered? 
And just the upper Part is made tapered?
Thank you for Help.

[PeterP]

Graham will probably pipe in on this. He tried the flag poles once and decided against using them because they were too heavy and not strong enough as Par mentioned. The combo mast is made out of aluminum lower section - which is untapered - and upper section made out of light wood such as spruce. And that is tapered. You could make that part hollow but I don't think it is worth the trouble. PeterP

[wasserboot]

Thank you Peter,  now i understand!
 

[PAR]

1.789 lbs. (.811 kg) per linear foot of 4" T-6 (6061) with an 1/8" wall. Multiply by the length of the lower tube and you have the weight. The upper section will take a little more calculation, but it too is fairly simple to figure out.

 

I made this exact type of mast with a C-17 build a few years back (single aluminum tube lower and birdsmouth spruce upper). It turned out light, strong and not too bendy.

[wasserboot]

Thank you, i found tubes 0,125" wall thickness that weigh 14 Kg at 16 feet length. That is really light. So i have to use light wood for the top...

[Howard]

My plan is to use 6061 aluminum entirely for both masts. No wood for three reasons. First is that wood is variable, and thus can't be predictably engineered (bend, weight, etc) so it is hard to predict performance, mainly bend. Second is the problem of finding lengths of clear spruce good enough to build with and the expense of it if I could. The doug fir mast I built for my spindrift weighs the same as the aluminum one, so I don't see any weight savings with fir. Lastly, is the maintenance issue. Paint, varnish, etc plus the sail track somehow has to be attached to it, so fasteners in wood, over time, could lead to water intrusion. Painted aluminum masts should do well for a long, long time.

 

Aluminum masts, to keep the same taper profile, will probably require three sections, so the weight will be less aloft. Main issue here is the need to "step down" the sail track over the joints. Alan Stewart covered that in his excellent video series for the CS15 kit, showing how to build the fiberglass ramps.

 

Those are my thoughts, not that they are right.......but that is what I intend to do and why.

[Chick Ludwig]

We used flag pole masts on my Princess 22 (PS-22) and they seemed satisfactory at the time. I do believe that the "stepped down" tubing as Graham is using now are better engineered and eliminate the concerns about the weakness of the flag pole masts.They may be a bit more difficult to assemble that the flagpole, but easier than the bird's mouth section. Does Graham have a plan for a stepped down tubing version for your P-26?

 

Alan's video of the process of fitting the sections together is very good. You could cut wood or "cutting board" plastic to make the "wedges" at the joints, or even stack washers between the track and the mast where they step down if you don't want to build the fiberglass wedges.

 

The water penetration and rot on the wooded section is  more of a problem that we probably realise. Alan may chime in here. Seems like he had a failure on his cat (?) because of this.

[wasserboot]

A mast made of 3 sections aluminum tubing is worth to consider. It will not look as elegant as an continuously tapered Mast. But it is a cheap and it seems to be a good working alternative to the carbon or spruce masts.
Good spruce or slow grown fir is not obtainable here or it is extreme expensive. So i will stay to aluminum
In my P26 plans there is only one birdsmouth version. It is completely made of wood or the version made of 16 feet aluminium tubing with a wooden or fiberglas top.
so i will find Alan´s video...
Thank you all !

[Howard]

I have seen masts from 3 stepped down tube sections on Tony's Princess 22. His looked and performed well. After seeing his in action, I decided to do the same with mine.

 

Process, I think, is basically the same as with other stepped down tubes. There will be a 1/8" gap to fill with wrapped fiberglass tape bushings (Alan demonstrated this too). Not sure what the overlap of each section is, but we can find out when the time comes. Difficult part is to find the 10 foot or 12 foot length tubes to start with. Places like Online Metals top out at 8 feet or so. I think Graham can get the longer tubes and that is where I'm starting the search for mine.

 

On other aspect of these will be to design the masthead fittings (or crane) for the halyards, etc. These will need allowances for any topping lifts, and in the case of the mizzen, for the mizzen staysail. I have a welder lined up who can do it, but I will need a good design. Most likely it will be "cap" made from tube and fitted over the upper end of the mast section.

 

If Alan runs out of anything else to do, perhaps I'll be able to talk him into building all this for me and all I'll have to do is glue them together.

[Chick Ludwig]

Graham specifies particular turning blocks for halyards that attach with bolts to the top of the mast tube. Other lines such as topping lifts could be attached with eye straps. I made a cap for the top from "cutting board" plastic. Graham has it all worked out---just ask him.

[LennieG]

Agreed. The CS 17 plans spell it all out with little room for mystery but great need to be able to read plans

[Chick Ludwig]

My favorite quote---"When all else fails, read the plans". Another favorite, "If it doesn't fit, get a bigger hammer." Or "I sawed it off three times and it's STILL too short". All words that I live by. Hey, how about this one: "i know he's the designer, but I've got a better way."

 

Maybe you have some "words of wisdom"?

[PAR]

Over the years I've noticed a trend in home built boats, the ability to read plans. When I started to build boats in the 60's, you got a set of offsets, some lines and some build details. It was assumed you'd read the plans and sort out the details in a shipwright fashion. As new techniques and designs started to appear in the 70's and early 80's, things started to change and the emphasis was placed on building to the instructions, not the lines or offsets. Now, many plans don't include offsets or even a lines plan, just panel layouts and "attach tab A to slot B" instructions. Most modern builders don't know how to read plans, particularly if labeled and notated with traditional nomenclature and symbolism. I find this a bit disturbing, but not unusual. In the same period, folks where building houses too and you'd get a set of plans. You'd buy a stack of 2x4's and plywood, using the plans place the pieces as required. Now, you get a precut kit, with the 2x4's and plywood marked, likely stacked on the pallet in the building order too. This is the part that bothers me. On one hand you get more boats (or whatever) on the water, but on the other, it's dumbing down the population to the point, of needing to nurse maid them through the process with a 40 page book of assembly instructions.

[wasserboot]

Thank you all!
When the time comes to build the Masts, i will ask Graham for an updated spar plan.
The one i actually have for the P 26 seems to be an early version.
I did some research in the www for aluminium tubes i fond this one in Germany(their website is in english too):
http://www.wmh-group.com/products/tubes-made-of-aluminium/dinen-round-tubes.html
As i understand their make length up to 20 meter.

Their Stock list is: http://www.wmh-group.com/fileadmin/stock_list/WMH_Aluminium_Round_Tubes.pdf

And they are loceted in the USA too: http://www.wmh.de/unternehmen/standorte/usa-incorporation/usa.html

A question to the Metallurgists: is it really so important to use 6061 Aluminum? or does another alloy they sell work too? Are the different alloys so different that is it important to get the only one?




 

[wasserboot]

Over the years I've noticed a trend in home built boats, the ability to read plans. When I started to build boats in the 60's, you got a set of offsets, some lines and some build details. It was assumed you'd read the plans and sort out the details in a shipwright fashion. As new techniques and designs started to appear in the 70's and early 80's, things started to change and the emphasis was placed on building to the instructions, not the lines or offsets. Now, many plans don't include offsets or even a lines plan, just panel layouts and "attach tab A to slot B" instructions. Most modern builders don't know how to read plans, particularly if labeled and notated with traditional nomenclature and symbolism. I find this a bit disturbing, but not unusual. In the same period, folks where building houses too and you'd get a set of plans. You'd buy a stack of 2x4's and plywood, using the plans place the pieces as required. Now, you get a precut kit, with the 2x4's and plywood marked, likely stacked on the pallet in the building order too. This is the part that bothers me. On one hand you get more boats (or whatever) on the water, but on the other, it's dumbing down the population to the point, of needing to nurse maid them through the process with a 40 page book of assembly instructions.

Hello Paul, I think i am able to read my plans and really found no hints about the 3 part mast made of aluminum.

It is not easy to work from imperial plans and the foreign language is sometimes confusing me.

Especially the nautical terms and special sayings, phrases and jokes that derogate from my school english that is long time gone...

But with the help of the internet and the kind people here almost every thing is possible..

best regards

Sönke

[Peter HK]

 

 

A question to the Metallurgists: is it really so important to use 6061 Aluminum? or does another alloy they sell work too? Are the different alloys so different that is it important to get the only one?

The mechanical properties do vary quite a lot between alloys and tempers.

As an example a common alloy for tube here in Australia is 6060 T5 which has an tensile strength of 150 MPa whereas 6061 T6 (the standard alloy for marine use) has a tensile strength of 260 MPa...over 70% stronger.

 

Cheers

Peter HK

[PAR]

To further Peter's comments, 6063 (T-52) alloy is common and an easy substitute, unless you look at the physical properties, which has it at 50% less tensile strength as the spec'd alloy 6061 (T-6). This is a huge difference, not just a subtle change.

 

Wasserboot, I provide plans with moth metric and SAE dimensions, but some don't. Given the smallness of the world now, I think it's only reasonable. This is a relatively recent thing for me and I remember making this transition and the trouble it caused me initially. It took some time, but I've gotten used to metric now, though admittedly, I still think of a couple of centimeters as an inch or a meter being a few inches longer then a yard.

[Howard]

Sonke:

 

You likely have the only plans there are, and while they offer a list of optional materials, the only one really discussed in any detail is to make the bottom 16 feet or so from aluminum and the top portion from wood. In short, you have the only plans there are and are reading them correctly. 

 

My reasons for deviating from those developed after I hitched a ride on a Princess 22, which has a similar rig. It seemed to work well and I seem to recall it being the then preference of Graham. This would have been a couple years ago, which would also have been 3 or 4 years after the plans you have were drawn up. As with many aspects of building these boats, there may be some known improvements or changes that people make, even if the plans have not yet caught up to the changes.

 

Hopefully, one or more of us will get to these before you do, so you will have tracks to follow. If not, we will solve it here together. By the way, there are other aspects of installing the tabernacles and masts and rigging the boat that will be more complicated than building these masts, so you have that to look forward to as well. The point is don't worry about it too much.