Making a boom tent for a dinghy...any advice?

[Greenheart]

Another idle low-season dream. But unlike my painting & refitting work in high-summer 2014, I'm planning to finish the tent ready for use before September...

I was given an old tent a couple of years ago...not new, not perfect, and so big that SWMBO and I will always prefer to camp in our cosy little 3-man Eurohike...

...so, is there any reason not to use its copious quantities of fabric, to create a boom-tent? I've really no idea whether land-tent fabric is equally suitable for boats.

I'm not thinking in terms of those vast square-ended things you sometimes see on Wayfarers in sheltered estuaries...they look too wind-catching to me...

...I'm thinking just a triangular-form tent, perhaps making use of salvaged GRP hoops to give a bit of convex shape to it, for better space inside and rain-resistance.

I don't plan on raising the boom much higher than it sets when sailing...so hopefully the boat won't roll and squirm alarmingly if the wind rises in the night.

Any advice or experience will be greatly appreciated. :encouragement:

 

[prv]

Surely the windage of a tent from the side doesn't change much whether it's square or triangular? All that matters is the height and the length? You'll have far more room inside if you make it square-ish.

What sort of tent is the one you were given? A ridge tent, a dome, or one of those big family-sized frame tents?

I take it you have a sewing machine?

Pete

 

[Kelpie]

From what I'm aware, the difficult thing is sealing up the front end of the tent, around the mast. If you expect to be lying to anchor or on a mooring most of the time, this will be pretty important.
Of course you could just start out simple, and rig up the sail slung over the boom. Someone went around the Med like that in a variety of Laser, IIRC.
Or how about a bivvy bag, for extra claustrophobia?

 

[duncan99210]

No reason not to use tent fabric to make a boom tent....

As to shape, the squared off shape will give you loads more room for not a lot more windage than one run straight from the boom. As you only have a single backstay the you could just run lines from the stays to the back stay giving a sort of triangular plan form to the tent for very little hassle and not need to use hoops or any other supports bar the boom. For weatherproofing the seams, you can get seam sealing tape at no great cost. If you need to access the foredeck, then a zip or two in this area would make life easier. Have fun and do put some pics up in due course.

 

[Seajet]

Dan,

I imagine it's a stand alone tent then, not the sort requiring a flysheet ? I think a fairly triangular pattern sound about right - the grp hoops wll be a boon I imagine - as it gives any side wind the chance to scoot over the top instead of presenting a flat face.

I'd try hard to incorporate a plastic window, for light as much as anything as they're nigh on impossible to see out of - but be careful where you put it as they generate condensation so one wouldn't want drips from it onto one's face.

Think I'd arrange to have the outer end of the boom slightly higher, so drips run down to the gooseneck / kicker; that would also mean a nice big exit for safety and possibly help weathercock the boat ?

 

[Greenheart]

Good thoughts, thank you gents. I was certainly thinking that a triangular form, rising from the gunwale to the boom, would present less of a slab of "sail", and that it would more easily deflect the force of a gust, than a vertical wall of polyester...but I don't know that for sure.

I don't have a sewing machine, but I sewed the reef in my sail last year without too many injuries, and I was really surprised at how successful my hand-stitching has so far been.

I am thinking that the foredeck spray-break which forms a vee with a point about 18" ahead of the Osprey's mast, could hold small hooks or plastic fairleads, round which a triangularly streamlined end of the tent could be secured. And thanks for the foredeck access idea - good plan, whether by zip or velcro.

The shape of the interior will make me glad I'm not tall...but I believe I'd prefer a robust structure stretched between fixed points, to a generously-proportioned square-cornered tent which flaps and fills with every gust.

The absence of backstays on the Osprey means there'd be nothing to support the aft end of a square tent's ridgepole. But my lazyjacks act like a topping lift, so I'll be able to raise the boom-height to take up any slack in the triangle - and to enable sitting upright under the boom without getting a crick in my neck.

The big tent I have is fairly modern, with a flysheet that almost fills a dustbin liner and an inner which is bulkier still. Lots of fabric to cut up, and with luck I'll be able to use some of the existing zips and pole-slots.

Of course, it won't be my plan to use the tent on anything but fine summer nights, in sheltered spots...but I've often been surprised how exposed sheltered spots felt when it's too late and too dark to break camp and start again.

I promise I'll show pics of my 'progress' here...thanks for the pointers. :encouragement:

 

[prv]

Lazy jacks - so you're not going to be able to drape the tent over the boom?

Hand sewing will work just as well, but it'll take about a million times longer

Pete

 

[Greenheart]

Lazy jacks - so you're not going to be able to drape the tent over the boom? Hand sewing will work just as well, but it'll take about a million times longer.

I was thinking (still at the theory stage) I'd use my 8ft tiller extension (necessary for solo trapezing) as a ridge-pole, with hooks or sail-ties holding the ridge-pole under the boom.

I fitted quick-release shackles between the mainsheet blocks and the boom this summer, and the vang unhooks in a moment, so the area below will be easily cleared.

Alright, it isn't a £200 carbon tiller extension, it's an aluminium telescopic shower-curtain pole. Pretty tough, though.

Yes, I was amazed at how long the sewing of my reef-patches took. Although the sailcloth was an ordeal to push a needle through, compared with polyester or nylon tent fabric.

 

[prv]

the sailcloth was an ordeal to push a needle through

Do you have a palm?

Pete

 

[Greenheart]

Nice. Last year I wrapped some insulating tape round my thumb, sticky side out...then about twenty layers, sticky side down, so it was a sort of soft thimble which I could re-use.

 

[Seajet]

Dan,

if your donor tent has a flysheet won't you have to use that, as the inner won't be water or wind proof ?

I have a feeling the lazyjacks are going to be a problem, even if you use the tiller extension as a ridge pole they'll surely be in the way; might be worth having a topping lift and slacken the lazyjacks right off once ties are around the sail ?

 

[Kelpie]

The usual method is to put the halyard to the boom end as a temporary topping lift, then sling the tent over the boom.
*If* you can be bothered, though, an alternative is to sew a series of ties along the ridge of the tent, and tie these round the boom, including the furled sail. This means that your potentially wet mainsail is not inside the tent space. I'm not sure how you waterproof the stitching where all the ties are sewn on though...

 

[Romeo]

My tent goes under the boom, with a line of ties to tie it up to the boom. The forward end does not go round the mast. An improvement on the trap I used to just sling over the boom.

 

[Greenheart]

I have a feeling the lazyjacks are going to be a problem, even if you use the tiller extension as a ridge pole they'll surely be in the way...

Not sure I can see why. The only obstructions below the boom are the mainsheet blocks and vang, and all of these these can be detached in about five seconds...

If I sew a couple of short webbing loops, one round the boom-end, the other at the gooseneck, these can hold the tiller extension (or better, my spinnaker pole) close below. And the pole can support the tent just as well as the boom...better, because I needn't move the lazyjacks, and the mainsail can stay in place, ready to hoist without delay or bother.

Dan, if your donor tent has a flysheet won't you have to use that, as the inner won't be water or wind proof ?

Quite right, I didn't think of that. But the flysheet itself is just massive...probably over 600 sq ft...so I should have enough. Might make myself a nice dark grey masthead asymmetric while I have the needle & thread handy.