This blog is devoted to my John Welsford designed 15' Navigator yawl Ellie. I built her in my garage over a period of 18 months and launched her in 2011. She sports a sliding gunter main, roller furled jib and sprit-boomed mizzen. Her construction is glued-lapstrake over permanent bulkheads and stringers. This blog is a record of her construction and her voyages here in the Puget Sound area and (hopefully) a useful resource for fellow Navigator builders.

Monday, July 13, 2015

How to make a boat tent for under $20

It's that time of year again.  Spring Tweak time!  I know, I know, it's more of a midsummer tweak.  Sorry, I'm way behind schedule this year.

This year's Spring Tweak is an inexpensive boom tent.
Most of the messabouts that I plan on attending this year require sleeping onboard the boat.  Unlike Sucia Island's abundant camping, many of the other destinations we like to visit have limited camping.  Saddlebag island, for instance, only has 5 campsites.  Hope Island, only 4.  Next week is the "Pocket Yacht Palooza", followed by a 4 day "Crooza" to several destinations which may or may not require sleeping onboard. It's also nice to have the option to tie up at a marina.  And there's always the possibility I could be late getting home and have to anchor who knows where for the night.  Having a boom tent onboard at all times really is a necessity. It doesn't have to be fancy in my opinion.  A quick and cheap one made from a tarp will do just fine.

So here's my version of the classic tarp-type boom tent.

After quick trip to the local Harbor Freight Tools store, I returned with this 11 x 15 foot cammo tarp for a mere $16.49, and a grommet kit for another $4.  $20 for a boom tent.  Can't beat that.

They also carry the classic blue and silver tarps too, of course, but let's be honest.  There's really only one choice here.  Not only does cammo look good, in a far-less-tacky sort of way, but it also enables one to go Stealth Camping.  Stealth Camping, in case you are unfamiliar with the term, is the practice of arriving late at night, mooring up to someone's private dock, boat, or any other no-camping area, and stealing away early in the morning before anyone realizes you were there.  I, of course, would never do such a thing ;-)

To support the tent I needed a ridgepole.  I lashed my boom and gaff together and use them as the ridgepole. My topping lift/jackstay line, and my peak halyard both prevent draping the boom tent over the ridgepole, so they get disconnected.  To support the ridgepole, I disconnect my mizzen halyard and connect it to the aft end of the ridgepole.
I measured the distance between the main mast and the point where the mizzen halyard connects to the ridgepole.  Then I cut two equal length slits in the tarp so that the distance between the slits was equal to that measurement.
That allowed me to drape the tarp over the ridgepole.

The next part is simple, as the famous sculptor Michelangelo allegedly once explained:
After marveling at Michelangelo’s statue of Goliath-vanquishing David, the Pope asked the sculptor, “How do you know what to cut away?”
Michelangelo replied “It’s simple. I just remove everything that doesn’t look like David.”
So I got out my scissors and trimmed away everything that didn't look like a boom tent.
I left some flaps at the front and rear of the boom tent so I could seal both ends off in a rainstorm.

The flaps can be rolled up and secured with a clip to keep them open, or tied down with a bit of rope to keep them closed.  I trimmed the sides even with my lower rubrail.

When I removed the tarp and laid it out flat, it looked like this.  Not an easy shape to define on a  drawing.  You can see why it really needs to be cut in-place.
The most difficult part about making a boom tent is coming up with a way to secure the sides.  Several methods have been employed.  Ropes can be strung under the boat from one side to the other.  Clips or snaps can be added to the gunnels to attach the boom tent to.  Ropes can be run fore-and-aft to provide an attachment point, and so on.  But the easiest, most effective, and elegant solution I have seen my friends use are sandbags.  Several small sandbags weighing about 1 lb each are fastened to the boom tent to weigh the sides down and keep them taught. They work very well and don't require a bunch of new holes to be drilled in the boat.

I didn't have enough time to make sandbags before our annual Sucia trip, so I improvised.  I used 500ml plastic water bottles instead of sandbags.  They actually worked quite well.
I drilled a small hole in the water bottle caps, tied them to the boom tent, and store the empty bottles under my front thwart.  When I need them, I simply reach over the side and fill them with seawater and screw them onto the bottle caps. The only thing I don't like about them is they tend to bounce against the hull at night, keeping me awake.  I think sandbags would be quieter so I plan on replacing them with sandbags soon.

My son Tim and I just got back from our annual Sucia Small Boat Rendezvous.  It rained off and on the entire weekend, but we were cozy and warm under this humble boom tent, using our sleeping platform

When we awoke in the morning, there were no signs of condensation or leaks anywhere inside the boom tent.  We were very pleased with the results.  Well worth the $20 to be sure.


  1. Great article, I am sure many will be grateful for your help with a thorny problem...well done :)

  2. Nice job, Joel. You even have an air inlet around the tiller.
    Steve Lansdowne

  3. Great! Thanks for keeping it simple and sharing 😄