Masts and spars

[Manie B]

Hi guys
would a epoxy and glass tube / pipe,
wrapped / laid up around say a 100mm = 4" pvc pipe
make a good mast.

Reason for asking is that it could be laid up so that it is thicker at the bottom than the top, and you could lay it up to any thickness required.

Or does a birdsmouth wooden mast simply work better

still talking about a gaff rig

[Fanie]

Hallo Manie, moet jy nou flippen staan en tegnies rook oor goeters hier ;)

A mast is not just a round piece of material standing upright on a boat. There are many things that has to be considered when it is put together, like are there rigging, wiring etc going through the inside of the mast, how is the sail hoisted, the size of the sail, the length of the mast, the fittings attached to it and how it is mounted to the boat (like glue or screw :rolleyes:)

It can be made from fiberglass, but it is not just simply a matter of fiberglassing a PVC pipe and bobs you uncle you have a mast. The direction of the glass layers is important, and so is the mast diameter for the length an so on.

A mast does not have to be thicker or thinner in any one place... unless you want it to bend like a fishing rod. Masts just look like that since you take the picture from below and since you're nearer to it it looks thicker... same with high buildings, they are built narrower towards the top :D Trees that became masts in their afterlife were narrower at the top, but only because it was difficult to turn the tree upside down so the thickness would sag towards the ground again.

Allu masts cannot be extruded from thick to thin what I know off. You will have to use different extrusions that could fit into one another to make it thinner towards the top.

Are you putting a mast on your wooden boat ? An umbrella would work just as well :D

[deepsix]

Hi Mannie, I dont have anwers to your questions, but here are some pretty cool ideas I have come across.

I was just looking through the "building a mast" thread on the catsailor.com forum. There is some interesting stuff about strip planked masts with ply, glass and carbon. It seems much simpler that the birdsmouth method.

Building a mast Catsailor forum (http://www.catsailor.com/forums/showflat.php?Cat=0&Number=134804&an=0&page=0#Post134804)
Gust Spar Gallert (http://www.gust.ax/gallery/mast/)

http://www.gust.ax/gallery/mast/08-02-25/p2190032-640.jpg
http://www.gust.ax/gallery/mast/08-02-25/p2190040-640.jpg
http://www.gust.ax/gallery/mast/08-02-25/p2200045-640.jpg

Dudley Dix also has some interesting things to say about steel masts for gaff rigs. After all if you can build good boats out of steel why not a mast?
Dudley Dix Steel Gaff Rig (http://dixdesign.com/FAQsteel.htm)

Dont discount aluminium based on the prices of professional riggers. I had a discussion about building a mast with a friend who is a professional rigger, it turns out that the actual extrusion is a small percentage of the final cost. Tapering, building sheave boxes, aerofoil spreaders, splicing, T-balls, backstay crane, gooseneck, anodising. All of these things take time and contribute to the cost of the mast. If you buy the extrusion from hulletts and do all the work yourself, and simplify everything, a conventional aluminium mast may be viable.

Fanie

Fractionally rigged masts are tapered, usually by cutting and welding or they are spun tapered. It is to make the mast bend correctly and also to lower the
CG of the mast.

A variable wall thickness would be ideal due to increasing compression loads. Also you will see some masts are sleeved around the gooseneck to increase the wall thickness to handle the kicker/vang loads.

EDIT : Sorry I forgot its for a gaff rig, most is not applicable

[TeddyDiver]

[QUOTE=Fanie;201660]A mast does not have to be thicker or thinner in any one place... unless [QUOTE]
Self standing...:D

[Fanie]

Fractionally rigged masts are tapered, usually by cutting and welding or they are spun tapered. It is to make the mast bend correctly and also to lower the CG of the mast
And also to reduce the mast mass momentum when the rig pitches - which could be substantial in rough seas. On the other hand, the leverage of the mast would prevent pitch-poling in rougher water.

Ok, I know that masts are tapered, but not when you wrap glass around a PVC pipe.

And one more thing, isn't it ideal when a mast does not bend ant at all ?

[Fanie]

I made my tri's mast from allu the microlite guys use, they sleeve into one another so I have 4 layers of allu, and it is still not stiff enough on 6 meters and that's on a small 12m sail. I can only imagine what the big(er) cat's 50m^2 sail forces are going to be in a strong wind. I'm sure the cat is going to plane ;)

[Manie B]

Hi Fanie
thanks for your reply

i am so frikken depressed - your post ABSOLUTELLY lifted my spirits thanks:D

i am unfortunately getting ahead of myself here
bending moments still appear in a mast - even if stayed
compression at base - and big time at the boom goose neck
top sway under the cap shrouds
so well no fine
how does a epoxy fibreglass tube perform

has anybody tried
i have read all i could on bird mouth wood etc.
aluminium WAY too expensive
and yes size does matter
rather a fishing rod than a umbrella:D

still on the gaff rig
38 / 42 sq main
24 sq jib
72 sq genaker

SURPRISE SURPRISE SURPRISE

5.7 KNOTS SPEED AT 6 KNOTS WIND - LOADED 4811 KG
CATEGORY BBBBBBBB

starting to become a very nice cat - heavy displacement - good speed in light winds - afordable - easy to build - hard chine boat - epoxy on ply - small motors

delftship also very good results
sailcad similar good results
days of manual calcs also good

[Manie B]

Geez i type soooo slooow that by the time i get back to the thread there are more posts:D

what i meant by thick and thin is
its like wrapping insulation tape around a pipe
first layer all the way up
second to 3/4
third to 1/2
fourth to 1/4
catch my drift:idea:

[Manie B]

Very interesting to read about the steel mast
surprising:D
goes to show hey
if you dont ask you will never know
thanks

[PAR]

A 'glass mast has been done before, though it has limited returns. First, it's generally more costly then more convention means, second, 'glass isn't particularly strong, unless you use epoxy and high modulus fabrics (which is why regular GRP lay-ups are so heavy) and then there's the flexural and fatigue rates, which are lower then most of the other spar materials.

Steel is a good spar material and was the first after wooden, used by old Capt. Nat in the 1880's on an A/C defender if memory serves me. Of course it's only practical on certain hull forms and those with substantial size.

A lot depends on size and intended use. Gaffers, tend to be heavier, with higher D/L's and slower roll moments, which is easy on the spars. In this regard an excessively heavy mast could be tolerated, but why, when better suited materials can be incorporated, with less cost and effort.

[Fanie]

Hi Par, the problem with some materials is that you have to sell the finished boat to obtain the mast :mad:

I'm sure with a proper design and carefully laid glass one could build a mast suitable for our purposes. I know Manie plans a cat similar in size to mine, and it's not going to be a racer so it may well work...

[Manie B]

Very interesting to read that a man like Dudley Dix has done the homework.

Nothing wrong with a steel mast for a gaff rig.

As he has desribed it - it is virtually the same size as i would require.

Cheap and i could most definately build it myself
thanks gents:D

[Fanie]

Which boat is this for Manie ?

[Manie B]

Fanie this is good reading thanks to our friend Deepsix

http://dixdesign.com/FAQsteel.htm
http://dixdesign.com/hb30.htm

[Petros]

You can build a fiberglass mast but it will have some drawbacks. Fiberglass, while less expensive, has a low elastic modulus meaning it is not very stiff. To solve that it becomes heavy. It is not especially strong either, also adding weight. It also does not stand up to sunlight very well so it will not last as long (this is true of carbon/epoxy mast too, they need lots of paint). A carbon epoxy mast would be light and stiff, but also more costly and fragile. I have read making a composite mast is not that difficult to make in a home shop.

You also might consider a laminated wood mast, it can be made lighter by making it hollow. It is relatively inexpensive building it up from smaller pieces, durable and you only need wood working skills, and lots of clamps (you will have to build an assembly jig).

I have also considered what it would be like to build up an aluminum mast similar to the way an aluminum airplane wing is made; ribs, stiffening stringers, and a thin skin all riveted together. It requires a pretty detailed structural analysis, but it too can be built with simple tools in an assembly jig. Though labor intensive, it should be less expensive in materials and much lighter than a standard extruded alum mast. It would be very strong and light. I may build one someday for the ocean going cat I will be building in my next life.

[M&M Ovenden]

I have been thinking about masts for my gaff rig aswell. In my case it's for a slightly heavier boat, 25 tons :) I have thought about carbon mast as a friend has a couple available. On a 50 ft stick it would make a huge difference in weight. My problem about a composite mast for a gaff rig is the amount of shock. I may be wrong as I'm by no means knowledgeable about composites but for what i know they are extremely resistant to flex, very rigid for the weight but don't like repetitive shock and friction. On a gaff rig the jaws "hits" the mast a lot. On every tack or jib the jaw twist a way that shocks the stick, same with waves and low wind, the jaws hit the mast. Wouldn't that be bad for any composite spar?
What about the friction of hoops or lashing? I'd love to hear opinions about this.
I pretty much given up the idea for the mast but am still thinking about composite gaffs. For the booms, well, gaffer want heavy booms so wood it is.

For our previous boats masts, 36 ft schooner, we laminated pine, which served us well.

Cheers,
Murielle

[Manie B]

Murielle i just visited your web site
great stuff keep up the good work
please if you get anywhere near a Gaff rig boat, take some pictures and post them, Thanks

[M&M Ovenden]

I have thousands of pictures of gaffers, I have been collecting them since I was a child. Now my husband and I do trips and detours to see or take pictures of gaff rig boats. Over all, about boats, the traditional working boats are the ones that passion me. I strongly believe that a picture is worth a thousand words. Are you looking for anything in particular in pictures, I might have what interests you. Otherwise, tough to pick :)

M

[Manie B]

Murielle thanks, great to hear about your pics.

What i am looking for are those little close up details of all the "parts" that make up a good gaff rig, mast, boom, yokes, gooseneck, tackle and and and and

I find many pics of gaff rigs taken from afar but the resolution is very low so when you zoom into the pics all detail is lost.

Many of these old sailors have tried and tested methods of doing things and that is what i am trying to learn more about.

Once again
many thanks for your interest

[DanishBagger]

Manie,

I thought I'd find some examples of how one _could_ go about this. My set-up is rather simple, but then again, my boat is very small.

I then thought, I'd find a few links and recommend Rigger's Apprentice, "Hand, Reef and Steer" and the "gaffrig handbook".

However, looking for great links, I found this, which tells you what you can find where, so that's a tad easier for me, but I think it will help a little:

http://www.messing-about.com/gaffrig/

Now, Murielle, the rest of us would still be interested in seeing some of those pictures.

Oh, you might also want to take a look at other boats such as luggers and catboats. They might give you some inspiration.

Speaking of: When my sails are shot, I will be trying out a high peaked lug-rig on mine.

[Manie B]

DanishBagger

Thank You

just what i needed for the weekend, some really good reading material :D

TGIF

[DanishBagger]

No problem, Manie - have a nice weekend :)

[M&M Ovenden]

For smaller traditional rigs, this is also I nice book for one who wants to rig. It's in French but also has a lot of images. It is comparable to hand reef and steer but concentrates on smaller boats and goes over different rigs, including lug.

http://www.chasse-maree.com/index.php/les-livres/bateaux-par-genres/bateaux-traditionnels/guide-de-la-manoeuvre-des-petits-voiliers-traditionnels/fiche-produit-detaillee.html

Otherwise I have started adding some gaff rig pics to my gallery but it's taking a while and the weather is too nice to not be working on my boat. So here's were I posted (quite faster) some rig detailed pics.

http://picasaweb.google.com/Pepe.Berrou/GaffRigs

I'll add some more when I come across interesting ones.

DanishBagger, the lug rigs are even more attractive to me then the gaffers. We have seriously considered lug rigging, but knew too well it was a bad idea for a boat of our size to be handled by two. To convince ourselves we went play with some heavy lug sails at sea....that treated us.

Cheers,
Murielle

[DanishBagger]

Haha, good point, Murielle.
The reason I'm thinking lugs is because of the nigel irens' Romilly, Roxane and Roanne (at respectively 22, 30, and 37 ft) supposedly have neato handling systems. Ok, it took carbon fiber to get there, but they're beautiful.

http://www.nigelirens.demon.co.uk/nid_CRUISING3.htm

(Oh, btw, the Maggie B is one beautiful gaff schooner, while you're there - I see you used to own a schooner! I like that)

On - I believe it was on the wooden boat forums - Ed Burnett explains how those rigs are set up. Perhaps I can find it again. Seems very simple (the lug doesn't tip and smacks someone on the head when you slacken the halyard for one …).

Thanks for uploading those pics on picasa - they're excellent :cool:

[M&M Ovenden]

We raced the Marie Ty's construction with a friend who had bought a Roxannes bare hull to be fitted. Both boat where worked on side by side at a friends shop. I think they are still mooring neighbors. The sticks for the Roxanne are absolutely amazing, I got the chance to weigh the mast, stunning! The owner gets the mast in place with bare hands and rigs it in minutes. That makes the boat a great trailer sailboat, perfect to transport from one sailing plan to an other, which makes inland sailing a little more diversified and weekend trips more exiting. The concept is great and it's a fantastic looking boat...maybe I should take a break this summer and ask for a sail, only ever spent time on it on the hard.
Maggie B is indeed also beauty.

For small size sail I wouldn't be worried about the rig weight. For my size boat, it is a serious exercise to raise a lugged sail. The loose foot also become a dangerous weapon on a big rig, worst than a big boom as it can have more erratic movements. I've seen one act with a broken sheet....it's scary!

Murielle

[DanishBagger]

If you get to sail with him, please make a full account on these boards :-)

I found the Ed Burnett comments, btw:

http://www.woodenboat.com/forum//showpost.php?p=676681&postcount=11

http://www.woodenboat.com/forum//showpost.php?p=676684&postcount=14

Both are taken from this thread:

http://www.woodenboat.com/forum//showthread.php?t=14090

Edit: In the attached pdf, there's a drawing of how the yard is set up.

[wetass]

Hello,
I build stuff as a hobby, not as a pro. Don´t know what You don´t know so here are some of my thoughts on the topic:
I have built several tubes with this method and they have all come out fine. Nothing in Your scale though.
The first was a test for building a big wooden mast. We only made a spinnaker boom. The length was about 5 metres, od 120mm in the middle and tapering to about 70mm towards both ends. The wooden battens were yellow pine and the edge with the groove was straight while the straight edge was tapered. The thickness of the wood was under 20mm. The piece turned out straight and solid. No mast was made due to lack of time...
The second tube was a sitka boom, lenght about 3.5 metres, od 80mm material thickness 16 mm, no taper.
Third tubes were small tests for a project not in this field, length 2 metres, od about 50 mm in the middle, tapers to both ends by both narrowing and thinning wood strips. Material thickness 7mm in the middle and a worrying 3.5 at the ends.
These have all been round sections. By making the side strips wider You can make sexier sections.
All tubes were glued with epoxy. All were wrapped in plastic and assembled using hose-clamps. You want the kind that can be tightened with an elecrtic drill. Tapering the top is no problem..
If I was to make a mast, I would sheet the tube in thin fiberglass-cloth to make sure that water doesn´t get near the wood. My opinion is also to keep all lines (hoists aso) if possible, outside the mast for the same reason. Moreover, I think that the sail track should be glued to the mast (no screws..), again to make the mast last longer. The wood strips should be pre-scarfed to make life easy. A couple of extra hands is good to have around during assembly.

Hope this helps.