What's in Your Ditch Bag?

New Tech Bights article now out in issue No. 135 of Small Craft Advisor magazine.

Hypothermia, and Cold Water Incapacitation

This might be somewhat vintage (https://www.soundingsonline.com/voices/hypothermia) but it's still very good information to review before the sailing season gets started...Looks like lean males fare the worst in cold water. My lower limit has been 60-degree (15 C) water on fairly sheltered water; maybe I should think about finding some warmer water.

Here's a good YouTube video of what could happen if you end up in the drink...Good thing there were rescue swimmers nearby...https://www.youtube.com/watch?v=J1xohI3B4Uc.

How to decide when it's safe(r) to head out? Add the water temperature and the air temperature. Here's a short blurb I put together a while back on cool weather sailing on the Bay...

If you're going out on a big boat, or a bass boat, and you don't get wet, then maybe the "100 rule" (air temp plus water temp greater than 100 means you don't need a wet or dry suit), will work. But if you are going to get wet, or think you might get wet, then you better be wearing polypro long underwear and poly or wool socks -- at the least.

A better rule-of-thumb for us is probably "120", air plus water temp. I believe that the season at Ultimate Watersports on the Gunpowder technically ended (due to insurance) when the water temps got below 60. In reality, they never operated before or after water temps were below 65 (shut down sometime in September) because they didn't rent wet suits and assumed that people would get wet no matter what they were renting or how good they were at kayaking, windsurfing, or sailing.

If the air-water sum is greater than 120 (e.g., 60 degree water, 60 degree still air), you're probably going to be OK if you dunk. And if the water-air temp sum is less than 100, you'd better have a dry suit, and training. And a good buddy boat and some emergency equipment. 

Centerboards and Flotation

My article on replacing the rusted-out centerboard in Blue Knot, my Potter 15, is published in Small Craft Advisor, Jan/Feb 2021, No. 127. 

If you find yourself in the same situation and need a replacement stainless steel board, send me an e-mail.

In the same issue of SCA, Mark Downing mentions the usefulness of flotation bladders in his article, "The Importance of Capsize Testing."

More on Flotation, and Masts

In a previous article I mentioned a couple of options for replacing or adding flotation to your boat. I pointed out that dry bags and wakeboat ballast bags were more economical than purpose-built flotation bladders. But since small boat folk are usually pretty good DIYers, how about making your own bladders? If you're interested, here's a link to Mik Storer's article on making them, www.storerboatplans.com/boat/sailing-boat/cruising-dinghy/diy-pvc-buoyancy-bags-and-dry-bags-for-dinghies-and-canoes/ .

Materials that you need:

• Bostik Unigrip 999 or 1669 adhesive
• 18 oz Hypalon PVC fabric
• Air valve

A good source for materials for making and repairing dry bags and bladders is NRS (www.nrs.com), a top dry bag and raft manufacturer, as well as supplier for river running gear. They sell fabric, adhesive, and valves. And they have a bunch of useful how-to pages...

• www.nrs.com/learn/clifton-urethane-adhesive-instructions
• www.nrs.com/learn/how-to-replace-a-raft-valve
• www.nrs.com/learn/install-d-rings-and-footcups
• www.nrs.com/learn/inflatable-repair-adhesives-guide

Sailrite (www.sailrite.com) is another good source of PVC-coated materials, typically used for biminis and tarps (lighter weight and considerably cheaper than NRS):

• HH-66 adhesive
• 18 oz Shelter-Rite fabric
• 13 oz Weblon Regatta

Since I'm pointing to him, I should also mention that Mik Storer is probably best known for his iconic Goat Island Skiff design. And if you want to know anything about how to build and rig a lug sail, and get the most performance out of it, his website is where you should start. I noticed that he also has a couple of articles on windsurfer masts used for spars -- www.storerboatplans.com/plan/gis/windsurf-mast-lug-yard-goat-island-skiff/ . He's one very frugal sailor...

Small Boat Flotation and Howard Hughes' Flying Boat

Some boats, like Boston Whaler skiffs and MacGregor powersailers, are built with flotation foam between the inner and outer laminations. Roger MacGregor was quite willing to flood any of his boats just to prove that they would not sink and would keep you safe, even though they were water-ballasted. And if you check out his old sales videos on YouTube, he even did it a few times. 

When the boat is not built with integral flotation, you might have to really look for it. For example, the “built-in” flotation on a stock Potter 15 consists of three parts. The easiest-to-see, assuming it's still there, will be two large blocks of styrofoam, one located beneath each of the cockpit seats. They keep the aft end of the boat afloat in the event of cockpit and cabin flooding. Each block provides about 3 cubic feet (1 foot x 1 foot x 3 feet long) or 192 pounds (3 cu-ft x 64 pounds of seawater per cubic foot) of flotation. Since the empty weight of a Potter 15 is about 500 pounds, the foam blocks in the stern are not enough to keep the boat afloat if it floods. 

The rest of the flotation is much harder to find -- because it is underneath the cabin floor. On the forward end of the boat there is a bulkhead that crosses the hull under the mast support. If you open up the cabin floor panels and look forward, you will see it. Foam fills the space ahead of this bulkhead to support the cabin floor and to keep the forward end of the boat from sinking. Unfortunately, without removing the floor or cutting an inspection port, there is no easy way to inspect the forward flotation. Fortunately, Potter's builder did provide a way for any water that gets into the boat to drain back to the cabin, where you can get at it. I estimate the volume of under-floor foam is 6 to 8 cubic feet, or 300 to 400 pounds of flotation. 

Add the three parts together and you come up with 700 to 800 pounds of built-in foam flotation. This is enough to keep even a loaded Potter from sinking, and there are old sales photos showing a young woman standing in a scuttled Potter full of holes in the hull. If you find that photo, note that there are no waves, it is nice calm water. Sufficient flotation is necessary, but not sufficient to keep you safe. Placement of the flotation -- where it is located -- is the other aspect that needs to be addressed. How many runabouts have we seen where the occupants end up clinging to a capsized hull? Because most of the flotation is under the floor, a big enough wave could roll a flooded hull and it will "turtle" -- the flotation in the floor now up high. So, the best flotation is up high -- near the gunnels -- to reduce the tendency to roll over. Since much of the flotation of a Potter (and many other small sailboats) is also low in the hull, they have the same predilection to turtle when flooded, especially if the centerboard is not locked down or is lost, and the mast fills with water. Steve Potter described capsizing his Potter 15, and explains why it happened (“Capsize at Clipper Cove,” Small Craft Advisor, No. 56, March/April 2009, page 22). His experience is applicable to a lot of production and home-brew small craft.

If you find that the styrofoam blocks in your Potter (or other boat) are still under the cockpit seats, be aware that they can work themselves loose, which is not a good situation. And if they got loose before you bought the boat, they might even be gone. Some Potters have been "customized" with hatches cut into the seats, and the foam was removed to increase storage for anchors or fenders. Yikes! Hope the hatch covers stay secured. So it is important to make sure that enough flotation is still in the boat, and that it is secure and not rattling around. If the blocks are loose, then you can try to re-secure them using a good polyurethane construction adhesive such as PL Premium (test to make sure that it doesn't dissolve the foam). If necessary, fabricate a suitable “wedge” (using polystyrene foam sheet) to force the foam block up against the bottom of the cockpit seat. 

If the styrofoam blocks are saturated with water (it's an "open cell" foam) or if they are missing, you might want to replace them. Extruded polystyrene foam sheet, which is closed-cell and won't absorb water, is available up to 2 inches thick. The 2-foot wide sheets are especially useful and each piece, 2.8 cubic feet of foam, is good for about 170 pounds of buoyancy. Build up a “block” and secure it using PL Premium adhesive. It is also possible to add even more flotation by sticking polystyrene foam to the bottom of the underside deck surfaces. And if you are planning some cool weather sailing, more foam can be used to line the inside of the cabin walls. In the Potter, it is possible to insert additional sheet foam between the cockpit seat back and the hull -- the best place for more flotation.

An option to sheet foam is to add flotation or buoyancy bags, which have become common on small boats, kayaks, and canoes (e.g., www.nrs.com/category/3049/kayak-touring/float-bags). In addition to adding buoyancy, these devices also reduce the amount of water that might fill the cabin or compartment. Buoyancy bags are not cheap, and the selection seems fairly limited -- there's just not that much demand. In contrast, dry bags, used for rafting and camping, are readily available from many sources and come in volumes of up to around 90 liters (seatosummitusa.com/collections/outdoor-gear-dry-bags/products/ultra-sil-pack-liner). And the prices are very reasonable. To replace a Potter 15's styrofoam block (displacing 3 cubic feet) you would need a flotation bag with a volume of at least 85 liters (1 cubic foot is equal to 28.3 liters), and a quality dry bag would run about $50. You can fill them with inflated play balls or beach balls -- they are very cheap (find them on sale in the spring), tough, and can be inflated using any pump with a needle. If you are old enough to remember Howard Hughes, you might have heard of his gigantic flying boat, the "Spruce Goose," so called because it was built toward the end of WWII using laminated plywood -- steel and aluminum was in short supply due to the war effort. 

After it's single test flight in 1947 -- for about a mile at a maximum altitude that was under a 100 feet -- the plane was stored in an air-conditioned hangar Long Beach, CA until 1993. It's now at the Evergreen Museum (www.evergreenmuseum.org/the-spruce-goose). Hughes had already survived several airplane crashes during test flights of his planes. So he filled the plane's cargo compartments with beach balls secured with nets to provide removable positive flotation -- just in case.

Unlike the "Spruce Goose," the most effective position for these flotation bags in small boats is probably at the level where the flooded boat will settle, around the gunnels. And they should also be secured so that they'll stay put in a capsize (unlike in the above photo).

How about attaching flotation to the outer gunnels of a trailer-sailer, like on the hard-bottom RIBs? A string of fenders can add a lot of flotation, but they are expensive. A 22-inch fender gives about 1/2 cubic foot of buoyancy and costs around $30, although you can frequently find them on sale. And if you can figure out how to lash it to your gunnels, Duckworks sells a 9 x 60-inch beach roller ($70) that can double up by providing about 2 cubic-feet of additional flotation (duckworks.com/beach-rollers/). Wakeboats use "ballast bags" that are rated by pounds of water. A 375-pound bag has dimensions of 14 x 65 inches, or 6 cubic-feet, for $100 (www.evo.com/fat-sacks/straight-line-big-bag-375-ballast). That's a lot of flotation if it is pumped up with air instead of water. Two 350-pound ballast bags (5 cubic-feet per bag, $135, at www.wakemakers.com/launch-pad-350-twins.html) would make ideal replacements for the styrofoam blocks in the Potter's stern.

For lots of reasons it's important to load the boat so that the heaviest items, such as water bottles, anchors, and chain rodes, are secured as low as possible, ideally between the cabin floor and the hull bottom. In addition, it is useful to store lighter items, such as clothes and sleeping bags, in sealed “dry bags” that are secured as far forward and as close to the deck as possible. This puts flotation up high and, together with a couple of flotation bags up high under the cockpit seats, should help keep the boat from turtling if it is flooded. If heavy weather is expected, right-side-up buoyancy can be further enhanced by securing dock bumpers to the gunwales using the deck cleats and railings.

And it’s worth repeating the obvious: the Potter -- and any small cabin boat -- has it's maximum amount of flotation in its cabin. If the cabin hatch boards are in place and the sliding hatch is closed during a knockdown, much of the green water will be kept out of the cabin, the boat will stay afloat, and it cannot turtle. Water inside the cockpit should drain out (make sure the plug is out, or is easy to pull out). I sail my Potter with the hatch boards in but the sliding hatch open, for ventilation and so that I can get to stuff in the cabin, and the odds are still excellent that a knockdown will not cause cabin flooding. And whenever the wind pipes up, the best insurance is to "batten down the hatches" and I close up the cabin.

The Potter 15, like many small boats, has a hollow aluminum mast and boom, which can help resist the tendency of the boat to capsize if it fills with water if the ends of the mast (and boom) are plugged. The spars don’t have to be “watertight,” even a wad of soft foam is better than nothing. If the mast is plugged it may slowly fill with water from all the little holes at the fittings, but until it does you have about a half cubic foot of buoyancy (30 pounds, or more than an typical inshore life vest), which should help keep the mast up off the bottom. If you sail where “turtling” into mud is a distinct possibility, then adding a masthead float (a la Hobie cat) might actually be the best solution, at the cost of windage and weight at the top of the mast.

In Roger MacGregor's sales video for the powersailer, was the ballast tank flooded, or empty Answer: flooded.

What I miss...

 Janes Island State Park, Crisfield, MD. April 2015

3-D Design

Like many engineers of my generation (I programmed in Fortran and know what a PDP-11 is...), I began my professional career using quad-ruled paper and lab notebooks with carbon paper. Eventually we got IBM-PCs and I learned how to use AutoCAD, the ubiquitous 1-D program that many of us started designing with. Around the time that my engineers were learning how to design in 3-D using SOLIDWORKS, I was focused on contract and engineering management. So I never learned the "real" stuff. So here's my version of "solid works."

The example problem here is to design a tablernacle for my Potter sailboat. After sketching out a bunch of ideas on that quad-ruled, I decided to just head down to the shop and knock something out -- a little model that I could hold in my hand and show my sailing buddies to get their comments. Here's what I built...

I used poster foamboard for the base and sides, along with some picture framing mat board to tie it all together. There are plenty of safe glues that you can find at Walmart or Staples. Today I would use my glue gun to speed up the construction process. The scale one inch to the foot and I made a little ruler that I could move around. I probably spent less time putting this model together than I did on my pencil scratchings.

Yes, this design example is simple. But I wanted to show that you don't need to use SOLIDWORKS to design a boat or to figure things out. That said, you DO still need to analyze the stresses and strains -- stuff that the computer can really help with analyzing and visualizing. And that's why the experienced design pros get the big bucks -- just another example of YGWYPF ("you get what you pay for").

Going; going; gone. Well, almost...

No, I'm NOT talking about politics. As I'm doing research on the internet, more and more of my bookmarked links lead to "not there anymore" pages. This post is to help me remember that sometimes you can still find information if you look for it hard enough. 

International Marine, manufacturer of the West Wight Potter sailboats until it closed in 2015, provided a treasure trove of information gathered from Potter owners and ex-owners. If you were a new owner of an old Potter, this website was invaluable (thank you, Ken Lange). When the company closed, the Potter lore appeared to be lost. Fortunately, most of the information on the old website still exists (for now at least...) using the Wayback Machine,

https://web.archive.org/web/20160401020516/http://wwpotterowners.com/

As a new owner of a 25 year old MacGregor 19 Powersailer, I found the "dougpile.com" website to be a great starting point for info and mods, including a copy of the M19 Owners Manual. The original website is gone, but most of that content is still at

http://web.archive.org/web/20161014125752/http://www.dougpile.com/mac19/

A couple of years ago, I found another great MacGregor sailboat resource. I spent time perusing the forums, especially the section of "mods," then dreamed of the mods that I would undertake on my new-to-me M19. After a few months, the website disappeared. The boat has been parked and the projects have been halted for a couple of seasons. 

Recently I went looking for a nugget of information related to outboards and prop selection using the usual Google search. Lo and behold, I found that the old Mac website has reappeared, with a new and sleeker front page, a lot of recent posts on the forums, and more mods. More fun this winter; and dreams of new Mac19 projects! Here's the link,

www.macgregorsailors.com

To give equal time to the Potter owners (or potential owners), the best forum that I've found is at at the Trailor Sailor website. Here's the link to the Potters (there are also forums for other brands like Nimble, Com-Pac, Montgomery, and Precision), 

https://forum.trailersailor.com//forum.php?id=2

Happy Thanksgiving.

Sunshade for a West Wight Potter

When the summer sun is beating down on you, shade over your cockpit can be a desirable addition on any boat, and a bimini usually fills that bill. But on a small boat, like my Potter 15, a bimini always appeared to be in the way. It makes it hard to see the sail; and it can make it difficult to get into and out of the boat. If heavy wind is heading toward my small boat, I’ve found that the best place for any extra canvas is stowed down in the cabin, not up on deck -- or attached to a bimini frame. And for a trailer-sailer that gets towed long distances, at highway speeds, a bimini is not only extra drag, but gets exposed to lots of road wear and tear. I need a better solution...

In addition to all the problems mentioned, I found that many lower-cost bimini tops are fabricated without zipper attachment flaps and must actually be de-mounted from the boat to remove the canvas from the bows. Therefore I felt it would be a good challenge to fabricate a sunshade that I could rig and unrig in just a couple of minutes. In addition, I wanted a sunshade that could be easily moved out of the way if I need to get a better look at sail trim, or whenever I’m maneuvering around the dock or setting the anchor. I had no requirement or need for a professional-looking rig. My guiding rules were function, simplicity, and flexibility. And since I didn’t have a bimini on my Potter, I was starting from scratch. If you’ve already got a bimini on your small boat, you still might want to keep reading. You can add an easily-removable sunshade to your existing bimini frame -- maybe when you decide to replace the worn-out bimini top.

Starting with the frame, you can “bend your own” with electrical conduit, aluminum or stainless steel tubing, or buy pre-bent components from Sailrite (www.sailrite.com). Low-cost plastic and stainless steel fittings are available from Duckworks (www.duckworksbbs.com). I recycled aluminum frame parts from a four-bow bimini that had been used on a bigger boat. For my Potter 15, a two-bow rig is big enough to cover the cockpit, so I had plenty of material to work with. Each bow consisted of two bent legs and a slightly curved middle section that locked together. I measured the width across the cockpit and shortened the middle section to an appropriate length. A plumbing pipe cutter and a small file was all it took to cut the aluminum tubing. The frame ended up a bit wider than the cockpit rails, which is fine because the aluminum bows have plenty of “bend” in them. 

The only challenge was attaching the frame’s legs to the cockpit railing (to avoid drilling holes in the coaming or the railing). The tubing around the Potter cockpit and the bimini bows are both one inch in diameter, but I could not find low-cost plastic bimini hardware, so I only had what came with the original bimini. Apparently it’s much more common to use ⅞-inch diameter tubing for biminis, and that is what I would choose if I had to buy and bend tubing. I could find stainless steel fittings for 1-inch tubing, but they are expensive. So instead I used a couple of small stainless steel hose clamps around the Potter railing to attach the primary (front) hinge points to the cockpit railing (see photo below).

Two-bow sunshade frame. The front hinge is about a foot aft of the cabin bulkhead

On many biminis the frame is constrained by adjustable straps -- fore and aft. Instead of these I added two diagonal brace tubes to support the primary bow using some ⅞-inch aluminum tubing from my scrap bin. Then I fabricated mounting blocks on the cockpit rails using polyvinyl chloride (PVC) lumber scraps and a couple of U-bolts from the hardware store, and attached the plastic hinge points to the blocks with stainless steel hardware. This arrangement worked well enough that I’m going to replicate it for the front pivots, instead of the hose clamps. These diagonal braces really stiffen up the frame when they are tightened up, in contrast to straps that don’t. 

Detail of rear brace attachment to the cockpit rail

When I’m towing Blue Knot for short distances and driving at low speed, the frame is strong enough that it can stay up. With the front bow folded back, it’s even strong enough to double as a boom gallows. As shown in the photo above, the rear diagonal braces have wing nuts so that I can easily adjust the fore-and-aft position of the blocks on the rail to change the height of the frame. When disconnected from the rear blocks, the frame folds aft, resting ahead of the transom, which keeps it out of the cockpit working areas, and it rests on top of my storage cuddies at the aft end of the cockpit (see photo below). This is also the mode that I use when I’m towing Blue Knot on the highway. The frame is down and secured to reduce drag and potential damage; and the sunshade is safely stowed below, out of the sun and weather.

Collapsed frame for stowage and long-distance towing modes

If I fold the shade frame to its forward position, it will clear the companionway hatch and rest just aft of the mast step. I can then easily access the lazarette storage compartments. When I’m out on the water I rarely leave the cockpit to go forward, so folding the frame up forward when not in use is perfect. I need to lift the boom to swing the frame under it, but that has not been a problem. And I’m still trying to figure out how to configure it as a dodger...

Frame in forward position clears the hatch and the cockpit. Ideas for a dodger in the future?

Now on to the sunshade…Sailrite has several excellent on-line videos on fabricating dodgers, bimini tops, and sails. If you are considering building one of their professional-quality kits, or if you want to take a crack at building your own from scratch, make sure that you see what you’re getting yourself into. For my sunshade I wanted something simpler than a “fitted” bimini top that is designed for a more permanent installation like on the big boats. All that I really needed or wanted was a flat sheet that would block the sun and not blow away. Something that would attach to the frame using grommets and bungee cord, both cheap and readily available, was good enough for my prototype. Sailrite has lots of good options for sunshade fabric, Sunbrella being the big boat favorite. But it is not the only option. I had been gifted a couple of yards of crisp Dacron sailcloth (an end-of-roll remnant, I’m guessing), and that was what I decided to experiment with. And since I’m interested in learning something about sailmaking (my copy of Emiliano Marino’s “Sailmaker’s Apprentice” is well-thumbed), I figured that making a flat sunshade would be an excellent project to practice broadseaming and edge treatments. 

I cut my sailcloth remnant in half and joined it side-to-side with a constant width broadseam. Now I had a piece of fabric wide enough and long enough to cover the cockpit. I rolled the rear edge and added three grommets along the length. Then I folded the front edge to form a “batten” pocket, with an extra hemmed edge for three more grommets. Short bungee cords through the grommets attach the canopy to the aft frame, and several more to the front. I inserted a full-length batten across the front edge that stiffens the canopy’s leading edge and makes it easy to roll it up when I want to stow it. The finished canopy length was about six inches longer than the distance between the bows, and I used a length of 2-inch diameter PVC pipe to stretch the fabric across the bows. Tension comes from two ⅛-inch bungee cords that run from the ends of the pipe, through an O-ring at the rear brace point, and forward to cleats on the gunwales. If the wind is light or moderate in strength, the front bow will stay down without extra help -- the weight of the batten and friction in the bow joint keeps it down and the canopy taut. If it’s windy, I add two more bungee cords to the front grommets to keep the front bow down.

Sunshade stretched between the bows, and tensioned by the bungie-roller setup

As I mentioned above, I can adjust the canopy height by moving the rear support attachment points and diagonal braces -- I can easily lower the frame to clear the boom while sailing, and I can increase headroom when at anchor. I can “rack” the canopy forward -- or aft -- by adjusting the width between the bows using the white strap that you can see around the middle of the bows. The roller-bungie tensioner keeps the sunshade taut no matter how far apart the bows are, or how tilted the shade is. 

Sunshade in “air dam” mode (that is, tilted forward)

If I need to check the sail trim or just want the canopy out of the way, I simply lift the front bow and flip it back (the hinge points have knobs so the resistance adjustment is simple). The bungie tensioner pulls the PVC “roller” neatly down along the rear diagonal braces (see photo below). This arrangement might also be good for downwind sailing (!). A light pull on the front bow returns the canopy back to shade mode. Easy peesy. 

Sunshade flipped back. Note roller tensioner action

When I’m done sailing for the day it takes about a minute to pop the front bungee cords and roll up the sunshade. The rest of the rig, including the PVC roller, can stay right where it is, ready to go, and everything is out of the way. And I’ve got great access over the forward gunwales for getting into and out of the cockpit. Removing and stowing the PVC roller results in a very compact bundle that I can bungee neatly to the bows (photo below). When I get ready to trailer the boat, I pop the bungee cords used to secure the sunshade to the aft bow and then stow the rolled up sunshade inside the cabin. Since the sunshade frame is aluminum tubing, it is not strong enough to use as a handhold. If I had used stainless steel, maybe. 

Sunshade rolled up and bungied to the frame

I made the sunshade purposely wider than the frame figuring that I can always make it narrower. But the stiffness of the sailcloth fabric and the rolled edges help keep the sides lifted; and the uncurved shape made the sewing much, much easier. All the seams were flat, straight, and easy to feed into the sewing machine. Adding a batten across the front really helps keep the sunshade flat, and I’ve considered adding one or two more battens to stiffen it even more. Since I roll the sunshade up using the front batten, they would not present any impediment.

I realize that sailcloth is an unconventional choice. Dacron is sensitive to UV and wouldn’t last long if used to fabricate a traditional bimini that gets daily exposure to the sun. However, on Blue Knot the sunshade will spend most of its life inside the cabin, until I’m actually out on the boat and need it -- just like my sails. And my sails are as old as the boat (I know, I know...it’s probably time to invest in a new set). As a reference point, my sunshade used about two linear yards of 36-inch wide sailcloth. When I last checked 36-inch wide 4-oz Dacron sailcloth from Sailrite was running around $10/yard. Wider (54-58 inch) Supercruise Dacrons were about $12/yard for 4-oz sailcloth and $17/yard for 6-oz. Duckworks lists 36-inch wide 4-oz Challenger Dacon for $9.50/yard. Fabricating another sunshade using tougher, UV resistant fabric would be a snap because it’s easy to sew a flat sheet of fabric, there are no zippers to contend with, and there are only a few grommets that need to be set. In addition to the already-mentioned Sunbrella, which runs about $23/yard for the marine grade, I would also consider TopGun ($15/yard) and Odyssey ($12/yard). I still have the original top that came with my donor bimini; and it’s in good shape. Therefore another option would be to repurpose that fabric for an improved sunshade.

Once I got the sunshade frame and sunshade figured out, the “idea spigot” opened up. When the boat is sitting in the driveway between outings, the canopy frame supports a simple boat cover instead of the sunshade. The cover (still under development…) keeps rainwater, leaves and other debris off the cabin top and out of the cockpit, which greatly simplifies my cleaning tasks and keeps the cabin much drier (read, less mildew) between outings. I used fabric that is typically used for car covers, Evolution, which costs about $12/yard from Sailrite. And, based on the advantages that I got with a simple cover, I can see a future project to design and sew a cockpit tent -- with mosquito netting -- that will help extend my cruising season.

Evolution cockpit cover draped over the frame