Towing with no cover

[bruceb58]

Re: Towing with no cover

It's hard to believe, but true.

Open pickup beds with the gate closed get better mileage, and boats will help the tow vehicle experience similar benefits when you tow them uncovered.

I agree with you on the tailgate up/down issue but it is way better mileage having a lid still.

Here is an article that talks about the tailgate up/down and the lid. The lid supposedly gains you 8% fuel economy.

http://www.trucktestdigest.com/TTDfeatures/FeatureTailgateUporDown.htm

 

[bruceb58]

Re: Towing with no cover

Full mooring covers can also be used while towing if designed correctly with good tight tie downs and reinforcements sewn in on all areas which contact cleats and windshield.

Here is a cover I made for my boat. I made it to tow with but still prefer my snap in cover for my towing since the snap in cover is a smaller package to deal with when i arrive at my destination.

 

[rjlipscomb]

Re: Towing with no cover

BruceB58, suggest checking with the manufacturer to be sure. I have towed with the mooring covers on, no problems (fortunately) but not recommended by manufacturer.

Not wanting to change the thread, but on your pic, there appears to be a big gap between your bow eye and bow roller. I believe that there should minimal if any gap between the two. What happens when you hit a bump? Looks as if the boat can jump forward possibly causing some damage. Just a thought

 

[Silvertip]

Re: Towing with no cover

The behavior of covers depends a great deal on the style of boat and the tow vehicle. The cover on the boat I showed a couple of posts back actually sucks down when towed with my S10 Crew Cab (bed has a lid). It is absolutely unaffected when towed with the Yukon. Boats that have a full windshield will likely cause some ballooning aft of the windshield because of the negative pressure (airplane wing effect) but again, depending on the fastening method and placement, it may be of no consequence. Another way to reduce ballooning is to have a canvas shop stitch a couple of loops on the "inside" of the cover. As the cover is installed, bungee cords can hook to the loops and attach to a tie down point in the boat to limit ballooning. That way there is no rubbing as there would be with external straps.

 

[JimS123]

Re: Towing with no cover

When moving/towing, Pickup truck beds and boats are better uncovered for optimum fuel economy.

Air trapped will swirl around inside the open area of a boat or truck bed (gate must be UP), and air streaming over this air will be unable to drag against the boat skin or truck bed.

A cover will provide a friction surface. Air will stream over and against the cover, and there will be pressure points and friction points all along the surface. Any cover that moves/flaps creates even more drag.

It's hard to believe, but true.

Open pickup beds with the gate closed get better mileage, and boats will help the tow vehicle experience similar benefits when you tow them uncovered.

Hard to believe for sure. Too much misinformation of the web. I rely on my 45 years of personal experience.

Tailgate up or down??? LOL....I wonder why they sell aftermarket plastic mesh tailgates to replace the solid original ones? Could it be for less wind resistance?

 

[bruceb58]

Re: Towing with no cover

Not wanting to change the thread, but on your pic, there appears to be a big gap between your bow eye and bow roller. I believe that there should minimal if any gap between the two. What happens when you hit a bump? Looks as if the boat can jump forward possibly causing some damage. Just a thought

There is no gap.

 

[bruceb58]

Re: Towing with no cover

BruceB58, suggest checking with the manufacturer to be sure. I have towed with the mooring covers on, no problems (fortunately) but not recommended by manufacturer.

Been towing boats for 30 years with full mooring covers on them. Before I started making covers, my mom made covers. She made covers as her job and I learned how to sew from her. If you make the covers correctly, there is no problem.

 

[H20Rat]

Re: Towing with no cover

Hard to believe for sure. Too much misinformation of the web. I rely on my 45 years of personal experience.

Tailgate up or down??? LOL....I wonder why they sell aftermarket plastic mesh tailgates to replace the solid original ones? Could it be for less wind resistance?

they sell them because people will buy nearly anything, especially when what they think is true SEEMS to be the logical choice, despite having absolutely zero training in fluid dynamics. Besides, those mesh plastic gates were mainly for style (or lack thereof!), and have gone out of fashion thankfully... The turbulence going through that snow fence tail gate probably made for the biggest mpg hit of any method!

There have been numerous reputable tests on tailgate/cover, they all agree on one thing, the difference in mileage is nearly within the margin of error. What they disagree about is which method is best. For every study that says tailgate down, there is another that supports the bubble theory and tailgate up.

 

[gypsysoul]

Re: Towing with no cover

OK, I am going to go out on a limb and say I don't think sinko is talking about a boat cover, am I right sinko. He is talking about the hard engine cover that some times double as a sunbathing deck above the engine. And to answer his question, Yes I had one blow off, and to make things worse. It was not my boat. my nephews motorhome broke down on the way home from the lake. the tow company would only take the motorhome and not the boat. I drove the twenty miles home grabbed my pickup and ran bake and got the boat off the side of the road. And being in hurry to get home was "speeding" and less than five miles from town a gust of wind caught the engine cover/sundeck and ripped it and the little hydraullic actuators right off the bed/cover assymbly. that was just seconds before it went air born and detached from the boat. after recovering the cover I discoverd there was a extra latch for holding it down during towing. my nephew never latched it becuase behind the motorhome he claimed he had never had a problem with nothing more than the hydraulic actuators holding it shut. luckily nobody following me and no injurys. a little road rash on the bottom of the lid. but not noticable when it was remounted and closed. I could be wrong but I believe that is what Sinko is Talking about. not a actuall boat cover. But for the record if I tow short distance I don't usually put the cover on to tow. But if it a long trip my cover is road rated and works fine.

 

[smokeonthewater]

Re: Towing with no cover

I posted just about the same thing earlier and then realized he is talking about putting a cover on to keep from losing the engine cover

 

[Philster]

Re: Towing with no cover

From Mythbusters of the Discovery Channel:

"Driving with the tailgate down actually increased drag on the pick-up and caused it to consume fuel faster than the identical truck driven with the tailgate up. It was later revealed that the closed tailgate creates a locked vortex flow that created a smoother flow of air over the truck. With the tailgate down, the trapped vortex was dissipated and the drag increased".

The backed up a real-world controlled study by visiting a wind tunnel and tracing the aerodynamic flow, which revealed why it works, and later revisited the issue when many found it hard to believe. The test was controlled, repeatable and backed up via a wind-tunnel study.

Google for episode 43 for results/info.

In episode 64 they revisited the issue:

"Using a calibrated fuel flow gauge, Adam and Jamie first Re-Busted the tailgate up vs. down myth (that down is better), then went on to test various other truck configurations (hard top, mesh tailgate, no tailgate)."

The mesh tailgate proved the most efficient means, because it allowed the vortex to form, but also reduced some leftover drag.

So, the best mileage is in this order.

>Mesh tailgate in place/up
>Metal tailgate in place/up
>Hard top
>other tops


I participate in a number of science advisory boards and am used to citing my references/claims.

 

[bruceb58]

Re: Towing with no cover

So, the best mileage is in this order.

>Mesh tailgate in place/up
>Metal tailgate in place/up
>Hard top
>other tops

I participate in a number of science advisory boards and am used to citing my references/claims.

I believe you have this backwards. According to the Ford engineer in my previous post, the bed covered had 8% improved mileage over an open bed.

In the Mythbusters segment they noted no difference between tailgate up, no tailgate at all and a hardcover. Of course their tests were at 55MPH and 25MPH so would have been nice if they tested at 65MPH like the rest of the country drives.

They also used a fuel flow meter without taking into account what amount of fuel was being returned to the tank by the fuel injection so the results of these guys tests are not very accurate.

Not sure where Philster gets his order but this is the youtube video. Notice that the flow meters accuracy is at 0.1GPH

http://www.youtube.com/watch?v=r3aqHbD-O9E

 

[Philster]

Re: Towing with no cover

Covered = cap or tonneau?

Their analysis:
- best = use tailgate "web"
- all the same = tailgate up, tailgate removed, bed cover
- worst = tailgate down


Putting the tailgate in the down position tends to increase turbulence and drag of the open box? said Jack Williams, one of Ford Aero Systems Engineering team when asked this question a couple years ago during an F-150 test drive. .

Dodge aerodynamic engineers, like those at the other pickup manufacturers, agree:

"Our wind tunnel data falls in line with industry conclusions - that the tailgate down configuration is significantly higher in drag than the tailgate up (around 2-3%),? says Mark Gleason, Supervisor / Aerodynamics at the DaimlerChrysler Scientific Labs and Proving Grounds.

?Although it seems counter intuitive, having the tailgate up acts somewhat like a deck spoiler on the trunklid of a fastback vehicle. The tailgate actually raises the pressures on the rearward facing surfaces of the pickup cab and the forward surface of the bed, thereby lowering the drag of the vehicle,? explains Gleason" Dodge aerodynamic engineers, like those at the other pickup manufacturers, agree.

"Our wind tunnel data falls in line with industry conclusions - that the tailgate down configuration is significantly higher in drag than the tailgate up (around 2-3%),? says Mark Gleason, Supervisor / Aerodynamics at the DaimlerChrysler Scientific Labs and Proving Grounds. http://www.trucktestdigest.com/TTDfeatures/FeatureTailgateUporDown.htm

?Although it seems counter intuitive, having the tailgate up acts somewhat like a deck spoiler on the trunklid of a fastback vehicle. The tailgate actually raises the pressures on the rearward facing surfaces of the pickup cab and the forward surface of the bed, thereby lowering the drag of the vehicle,? explains Gleason. http://www.trucktestdigest.com/TTDfeatures/FeatureTailgateUporDown.htm

?Testing conducted by SAE confirms this condition, estimating an increase in vehicle drag of 2-3% with the tailgate down. Testing also shows that, counter to advertised claims, mesh tailgate replacements will degrade vehicle drag even further.? http://www.trucktestdigest.com/TTDfeatures/FeatureTailgateUporDown.htm


?Tonneau covers on pickup boxes do reduce aerodynamic drag,? says Williams. ?We?ve seen reductions of about 8- to 10-percent on the F150. The average fuel economy improvements for EPA city/highway cycle should be about 2-percent. The average steady-state (cruise control) fuel economy improvement at highway speeds should be about 5-percent.? http://www.sema.org/main/semaorghome.aspx?id=57004

 

[Jeff-in-PA]

Re: Towing with no cover

To the original poster, if you are worried about the engine cover or lid flipping up, simply put a strap over the front of it from trailer frame rail over the boat to the other trailer frame rail. The inexpensive 1" rachet straps would eb perfect.

As far as towing with a cover, I always tow my 18' open bow with the front covered and the cockpit cover on. Both poles are in place too. The front cover has push snaps except at the walkthru where it has twist buttons.

The cockpit cover is all snaps except at the rear of the side windscreen where it meets the fiberglass where there is one twist button on each side.

I've towed at speeds slightly over 75 mph and also at 65 mph with extremely strong cross winds ( JimS123, just south of border on Rt 81 south ) with absolutely no concerns at all for the covers staying on.

Jeff

 

[northernmerc]

Re: Towing with no cover

One likely could open a marine supply store with all the stuff that blows out of and falls off of boats along the highways! A cover may help keep all that stuff in place.

Our SeaRay bowrider came with a Sunbrella rain and sun top, with zip out plastic side windows. The part that covers the bow snaps in place. The back section of the top zips out, allowing one to leave the main section up for sun protection once at the lake. For towing, we usually just zip and snap the pieces in place and close everything up tight. Nothing flaps much as wind can't get in, and the top is still in good shape after years of use. Sometimes we tow with the top stowed in its storage spot that extends from side to side above the motor. Either way works fine.

We also have a heavy fitted canvas type cover that extends part way down the sides of the boats. It has an elasticized hem and various tie down points. That's good for keeping dust off the boat in the garage during the winter. But I don't like it for towing; it flaps a bit and then one has the problem of what to do with it once arriving at the lake.

 

[bruceb58]

Re: Towing with no cover

The instrumentation test run by Mythbusters was ridiculous.

They are stating that @ 55MPH they are burning 5.0GPH. The comes out to a whopping 11MPG. That was a small truck and even with a 5.4L should be getting better than 16MPG. Their test is basically worthless because they obviously weren't measuring fuel flow correctly.

Comparing a pickup truck bed aerodynamics to an uncovered or covered boat is also flawed. When a boat is covered, there is a slope from the windshield back to the stern of the boat. This is not unlike how every high performance sports car is designed. I am sure Chevrolet has done enough wind tunnel tests to determine that it is better to have a sloping back on the Corvette that to have a pickup truck bed back there.

 

[rjlipscomb]

Re: Towing with no cover

...Comparing a pickup truck bed aerodynamics to an uncovered or covered boat is also flawed. When a boat is covered, there is a slope from the windshield back to the stern of the boat. This is not unlike how every high performance sports car is designed. I am sure Chevrolet has done enough wind tunnel tests to determine that it is better to have a sloping back on the Corvette that to have a pickup truck bed back there.

I'll chime back in here with Bruce. Most, if not all, of the surfaces of a boat are different than a truck. We can understand how the air flows over a truck cab and in the bed and all of the effects, however, they are not the same for a boat. Most boats are naturally more aerodynamic. The underside is designed to ride smoothly thru water. The tops are sloped to move air over and around the occupants in the open cockpits. Air gets trapped in the cockpit and circulates and stuff blows out. Experience has shown that the engine cover can and has been pushed/pulled up and blown out due to a failure in design or simply over worn materials. It shouldn't happen at normal boat operating speeds or while towed at those speeds. Some of drive faster and increase the pressures (way too many to discuss here) and **it happens.

My recommendations:
1. Use a cover that is specifically designed and manufactured for trailering at highway speeds. If you made your own, great! good job and best of luck with it. You are the one guaranteeing it meets the requirements.
2. Do not expect your manufacturer supplied mooring covers to withstand these pressures. These covers were simply designed to keep bird poop and rain water out. All it takes is a quick review of your owner's manual to know.
3. It's your boat, cover and money... spend it however you want.
4. If trailering without a cover:
- Secure all trash and loose items,
- Physically check all materials and covers to insure they are tight and secure,
- Make sure all manufacturer supplied straps and tie-downs are in place,
- If something feels loose or you are unsure, secure it it with alternate means

Otherwise, let the rest of know when and where you're going so we can collect stuff and take pictures for future posts.

And, have a great boating day!

 

[Utahboatnut]

Re: Towing with no cover

I wonder if the results would change if the test vehicle were pulling something. Like would pulling a boat put a different wind turbulance if the gate were down or up or if there were a cover over the bed. In the end I do know that I have never had anything blow out when trailering with a good travel cover, but have had lots of stuff blow out traveling without one...

 

[Dave Abrahamson]

Re: Towing with no cover

One thing that nobody has mentioned yet regarding the whole tailgate up/down deal is the integrity of the rest of the pickup bed with one end of the box removed (or down).
Take a cardboard box and remove one end (or cut 2 sides and hinge it down).
The remaining sides lose rigidity and flex quite a bit, especially near the open end. I don't know about ya'll, but my experience has shown me that when you bend and flex metal over and over again....it weakens and something usually breaks,(welds, seams etc...).
I'm thinking there's a lot of flexing of the bed on some of the bumpy back roads we travel on to the local lakes.
Ever seen some of the old beaters on the road without tailgates? I don't know what's hodling on the sides of the beds on some of those things. Not much.
THAT'S the main reason I leave the tailgate up...but that's just me.
Interesting reading BTW.

Dave

 

[bruceb58]

Re: Towing with no cover

I am not sure why the whole pickup tailgate up/down was even brought into this discussion. It does not even apply here.