2 mpg improvement on tow vehicle

M

Marco Flamingo

Active member
Colby just posted about not towing with his boat cover because of increased windage. I have kind of the opposite. It all started two years ago when I was heading to Lake Powell. I thought I might want some kind of a shade for the fore peak hatch. I had some Sunbrella left over from when I removed the stock V berth cushion. Then I thought that I could fashion something that would also protect the cabin window from bugs and rocks. Bugs are a hassle when I get to a launch site and have to spend the time and water to clean them off before launching. Rocks are a problem because I had heard of people hauling in to remote launches on Vancouver Island and finding that their windshield was cracked from gravel on the logging road.

As I worked on it a little, I also realized that a large cover from just the cowling to the bow would also work as a wind deflector. My cabin sits just high enough over my tow rig that I'm sure it works just like a parachute at 60 mph. I made it extra stout (although with used Sunbrella) and went off to Lake Powell.

I had kept track of my mpg while towing the boat for over 1,000 miles. Average was 20 mpg. With my wind deflector, I got 22 mpg down to Lake Powell. I was getting the same on the way back, but up by Moab I got into a wind storm. I slowed to 50, but the wind coming at me was also 50 mph. At an effective 100 mph, I tore up my little gizmo.

So I made a new one out of reinforced polyvinyl . It is a little bigger and wraps around the cabin a little better. I'm hoping for 23 mpg!! Of course, it cost me $50 to make, so I need to drive thousands of miles to make it pay for itself. Shouldn't be a problem. And of course, no more bug splatters to clean up.

Mark

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I'm truly impressed. What are you towing with that you get 23 mpg? Even though it's a 16' boat, it's gotta weigh something.

That's just under the best we get with our Toyota Camry, and a lot more that the 8 mpg we get towing Journey On.

Boris
 
Mark, Very interesting--thank you! I just have had windshield covers which snap on the sides of the windshield.

What reinforced polyvinyl material (source)--did you sew or heat seal/grommet the reinforcement? Can you give more information about the construction details.

The 18 wheelers all have a deflector over the sleeper to help with the aerodynamics of the trailers. I know 5th wheel owners who put a deflector on the truck.

Maybe we all need to have this type of deflector--for fuel mileage, and protection of the boat.
 
I've been thinking for a while of making some kind of cover for just the boat's windshield when trailering it long distances. Mostly to keep it clean, and to protect it from any small pebbles thrown it's way. I also like the bow protector that I believe Jay of Hunky Dory made. Projects for a later time I suppose. On long distance trips, I usually take the full cover with me, even if I'm not using it, just in case. I would most likely put it on if I was traveling where there was a lot of dust or snow & ice. As for the mileage difference, it takes away about 1-2 mpg, depending upon the wind direction. Colby
 
You need to be careful of damage to the gel coat from edges of your fairing flapping in the wind at highway speeds.

I have a bare spot on my engine that the PO says was from an earlier boat cover flapping in the wind sometime during a winter while the boat was in storage.
 
Colby

Look at Photos:
Cruises and Events:
Mississippi River 2011:
Page 3:
Photo 49&50:
Then check the rest on that page to see if you recognize anyone.
Terry
 
ssobol said:
You need to be careful of damage to the gel coat from edges of your fairing flapping in the wind at highway speeds./quote]

Hopefully, I took that into account. On the finished cover (the picture was during the fitting stage), the grommets have a thick nylon webbing through them to keep them away from the gel coat if the cover flaps. The leading edge is forced down completely across the front lip of the cabin and should not flap. On my initial cover, I did have a black nylon strap that flapped against the cabin wall. It left a black smudge what was easily cleaned off. That told me that, as to nylon vs. gel coat, nylon is the sacrificial material. It's hard to see in the picture, but the cabin side to deck cleat connection has a foam net float at the top to work as a stand-off from the side of the cabin. This is where the original strap rubbed on my first smaller cover.

My tow vehicle is a Santa Fe Sport. It has a 2 liter 4 cylinder turbo. 264 hp and 269 ft lb torque when I need it. The trick is to not need it too much. If I pretend that the boat and trailer aren't behind me (which is easy to forget), I'm sure that I could think "Wheeee" and get 16 mpg. Mountain passes are not an issue. This model came with a factory #3,500 tow package.

The material is glued ala repairs on an inflatable. My sewing machine won't do this material, and my initial destructive testing of glued edges (no seams on the large panel) were impressive. On both sides of the GoLight are Dot fasteners to ensure that the center won't be pulled down. I haven't taken it for a road test yet. I'll get more pictures today.

Mark
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Mark, Thanks for the information--I had also wondered about the "flapping", but agree that with the design it should not damage the gel coat.

What is the name of the Polyvinyl material, and source? Are the "Dot" fasteners the stud and cap (snaps), the Common Sense (turn tab) or" Lift the dot" (All are made by the "Dot" company.)

Great job! Thanks.
 
Hey Terry, interesting setup.

travel_canvas.jpg

But I think that monster in front of it is protection enough! lol

Terry_s_land_cruiser.jpg


Brings back some memories. I believe that was my first C-Brat gathering! Colby
 
Bob,

They are the Common Sense type. The polyvinyl is from Seattle Fabrics (I love that place).

http://www.seattlefabrics.com/PVC-Coate ... _c_65.html

I had used the 15 oz PVC in the past to make semi-clear dry bags for kayaking. It really helps to be able to see through a dry bag. After a few days, I can't remember what is in different color or size bags. I have started to use the thin coated-nylon dry bags that are so cheap on the CD 16, but they can't take any abuse. I put label tags on them.

The trim material is a combination of 10 and 18 oz. stuff from my old scraps. The glue, as one would expect, is some horribly toxic stuff. The material is scuffed with sandpaper and cleaned with Toluene before the glue is applied. This time, I used alcohol and it seemed to work fine. The glue is applied to both pieces, then stuck together, then rolled with a roller. I put down some heavy paper because I was working on a vinyl floor. If I had glued my project to the floor I would have been in trouble.

Mark
 
Thanks Mark--that 15 oz with Scrim appears to be identical to what my over 35 year old "Sea Line" ditch bag is made of. That bag has taken many licks and is still in great shape--good choice!

Do you use any special technique to keep the ends tied to the bow rail from sliding up?

Also, after looking at the webbing, I wondered why the nylon vs polyester. My thought is that the polyester might have less stretch (?).

I love the Common Sense fasteners--but cutting the material is not easy. (I borrowed a punch when I was using a lot of them--and my friend may still have the punch. I have free cut a few with a blade on a 150 watt soldering iron, which seals the edges, but takes more time.

You did a great innovate job. Maybe we will see more C Dorys with this feature. It could also be used to give ventilation with the front window and maybe the hatch open during rain at anchor or the dock.

Again--thanks!
 
thataway":2axkj2uj said:
Do you use any special technique to keep the ends tied to the bow rail from sliding up?
Click to expand...

The rail seems perfectly placed for this connection. It can only slide up or down an inch or two and, on the previous one, the air pressure pushed down and they didn't move.

Seattle Fabric and Sailrite sell that special punch for the Common Sense fasteners. I didn't get it because I was only doing a few. But I did learn that whatever the fibers are in the vinyl, the grommet punch did not like them. I actually had to sharpen my grommet punch after doing a couple of holes. I'm not sure how easy it would be to sharpen the special $70 punch for the fasteners. I just used an EXacto knife for those.

Mark
 
thataway":l4mnanzc said:
The 18 wheelers all have a deflector over the sleeper to help with the aerodynamics of the trailers. I know 5th wheel owners who put a deflector on the truck.

Maybe we all need to have this type of deflector--for fuel mileage, and protection of the boat.
Click to expand...

When I was first looking at this idea, I checked out RV and commercial trucking articles. There are some very expensive roof top deflectors for vehicles towing a big travel trailer. The reviews that did actual mileage comparisons generally said that the deflector doesn't work because the trailer is too far behind. Most said that it was not effective after about 8 feet. A big deflector on a tractor trailer rig, or a deflector on a pickup pulling a fifth wheel trailer, might be close enough.

But the aerodynamic feature that routinely produced better mileage was rounding off or even "sharpening" the face of the trailer. One article was somebody who hauled a show horse around the country. Adding a kind of unattractive tall wedge-shaped storage locker on the front of the horse trailer made a difference when their roof-top deflector did nothing.

I thought about something hard, like 1/2" plywood. Sounds weird, but if it had a hinged V shape and was properly fastened down, it would work and could be folded and stored in the tow vehicle.

Mark
 
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