MYOG Tarp – measurements for modifications with front beak?

[Judith Humbert]

Hello,
Looking for a modified tarp design with front beak and rear triangle setup that will withstand NZ's mercurial weather. Wondering if this will work or if anyone has sewn or used a similar type shelter:

Ridgeline length: 102"
Baseline length: 96"
Front wall width: 42"
Rear wall width: 24"

Think it's going to take around 4.1 metres or so for this design. May have to put in a catenary ridge line to keep it from sagging and I'll put in a triangle at the end to keep wind and rain out. Wondering if the 42"-24" ridgeline pitch is going to be a bit extreme and how it may affect setting it up.

Would anyone know how to calculate beak measurements for the front? Or have any suggestions for a detachable beak that might also be used as a rain cape?

Fabric:
Here in NZ CN5 cuben (1.68oz/SMSY – $45/metre) or a variety of ripstop nylon ($20-30/metre) is available from a local sailmaker. They kindly offered samples of different weight nylon to test for water resistance, but said some of them stretch quite a bit.

I've looked all over Auckland for silnylon, etc. and this is the only local source for very lightweight fabrics found to date. CN5 (47.6g/SMSY) is the lightest cuben found around here and looks to be similar in weight to 1.43 oz/sqyd offered by overseas suppliers.

Any suggestions, comments or MYOG links greatly appreciated. So far I've searched through this site using "tarp design", "myog tarp", and "myog, Patrol Shelter" and rechecked designs from previous years but have yet to find anything close to this.

Much appreciated and thanks so much!

[Jerry Adams]

Will owfinc.com, thru-hiker.com, questoutfitters.com, or hammockgear.com ship to you? They have silnylon.

You must be talking about a tarp like http://www.mountainlaureldesigns.com/shop/product_info.php?cPath=21&products_id=85 (Grace tarp)

Is 24" the distance of the tarp from the ridge to the edge at the foot?

And 42" at the head?

What is baseline length?

What do you mean by Mercurial weather? windy and rainy?

[Elliott Wolin]

If I recall Ray Jardine includes formulas for beak size calculations in his first Tarp Book. I think they didn't make it into the revised edition. Contact me if you can't find the book, I think I have it laying around somewhere.

[dale stuart]

you might look at this design, http://www.sixmoondesigns.com/make-your-own-gear/night-wing.html. I made one with the mesh and a tub floor. Tub floor allows you to spread it wider (due to the roof up higher and tub floor blocking splash back over the cantilevered mesh)but you need to redo the cantenary curve. My floor is 88"X 52" with 5" tub walls + cantilevered mesh allowing 16" min front internal side walls and room for 2 people. It weighs 24 oz with guy lines.

With beak deployed showing front vent. (pardon messy garage and hasty poor pitch.
-Dale

[Judith Humbert]

Hi all,

Jerry – mercurial weather, especially this time of year in NZ, can mean anything from a nice day all day long or a day that repeatedly flip flops back and forth with any combination of rain, high winds, sun, etc. I have seen rain go nearly horizontal here in near gale force winds, hence my concern around a design that will deal with this kind of weather.

Elliott – thanks very much for your kind offer re: the tarp book to help out with beak measurements. If there's any info there on how to calculate said measurements that would be a great help!

Dale – thanks very much for the suggestion for the Six Moon Designs pattern. Your tarptent looks pretty cool!

I've nearly finished the tarp. Had it set up in the yard this morning to figure out how much fabric to take out of the beak to it will pitch properly. Now I'm waiting for a decent rain storm to see if the spinnaker nylon will actually keep everything dry.

Really appreciate everyone's comments and suggestions.
Have a good day out there…

[Author]

Posts