Gross Vehicle Mass

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Ozzie
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Gross Vehicle Mass

Post by Ozzie »

Most 563 owners are probably aware or their vehicles towing capacity and the rating of your towbar. Back in my first days on the "other" place, when it was happy, I contributed hopefully fruitfully to a discussion on towing and on GVM or Gross Vehicle Mass. I'm not an expert on the subject , nor much else for that matter, but it became apparent during that thread that many people don't understand GVM which is relative to towing large boats ( ie boats that are large relative to your vehicle). It's even relative to when you're loaded but not towing anything.

It came up recently again for me in regard to other matters not related to towing that a won't bore you with here. But I thought it might be of use to mention it here for those who may wish to know about this very important subject .

I'll use round figures for ease of explanation but put simply every car has a tare weight as stated on your rego . This is its unladen weight (with 10 litres of fuel) before you put even a paper clip in it....or yourself. In the end the tare is irrelevant it's the GVM that matters.

Your car has also a GVM which is the maximum weight allowable for that vehicle with everything on board . This includes you, your passengers, all your stuff and your BALL WEIGHT .

Don't bother my mate already made that joke ;)

This is the down weight on your towball from your towed mass. Ideally this should be 10% of your total trailer weight, but this is not strictly mandated by regulations so there is some flexibility.

Now the really important thing is that many people seem not to understand GVM.
If you have a tare of say 1900kg and a GVM of 2500kg your payload is 600 kg. Sounds like a lot, dunn'it, hold that thought. There are many accessories available for vehicles now and adding them contributes to your payload. This is particularly an issue for 4wd and RVs . Add a steel bullbar , say 90kg, a towbar, say 40 to 50 kg, a roof rack, cargo barrier etc. ok now stick your outboard in the back of your wagon. You and your wife, well that's 140 kg for us, your kids or worse still your two mates who are front row forwards, a full esky and everyone's sailing bag. Now, let's get ridiculous. I did a quick check on stuff the other day when I was looking at this . I have two floor mats on the front of my falcon, they are heavy duty 4wd mats and alone weigh 5 kg.

So what you say 5 kg?. Well, I had a mate who was in a hot rod club years ago, and one night they were at the local hangout, one of the members truss roofed garage, where he kept his spares. Suddenly the ceiling caved in and deposited the stored contents on them all. The owners comment " but I only had light weight stuff up there". Moral...100 items weighing 2 kg weighs 200kg.

Get to know your normal loaded up weight of your vehicle and what spare capacity you have for towball download. Why ? Well if you exceed your GVM and have an accident you may be up a famous creek. Not only without a paddle but insurance cover as well. Not just your comprehensive insurance but also your third party green slip. Injure someone or worse and you might say goodbye to your house.

What prompted me to post this is an estimate I read that there are a high percentage of vehicles on the road regularly exceeding the gvm. Don't take my word on any of this but please do your own research. A weighbridge ticket locally costs $27. May be money well spent. Cheaper than losing your house anyway. I bought a towball scale from supercreep last time they were on special for about $50 . Spritzigs ball weight was 120kg with no outboard . Technically spot on.

I'm happy to go into the subject further particularly regarding trailer loading relevant to ball weight . As I said I'm not an expert . I spent another life in road safety so I often saw the end result of failures rather than the preventative end. There is much info on this matter on the net and it's worth reading all of it if you are unfamiliar with the subject.

You can google the state transport nasties in your state and then "car weights" or go to carsguide.com.au and "vehicle weights explained"

If you have any other first hand , professional or legal insights into this matter please add the info . I'm up for any additional knowledge on this subject I can get.
Ozzie
Investigator #143 "SPRITZIG II"

The Mariner - “It’s too strange here. It doesn’t move right." ...
Enola - “Helen said that it’s only land sickness."
Waterworld (1995)
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Ozzie
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Re: Gross Vehicle Mass

Post by Ozzie »

As this topic has had 123 views I thought I would add a bit extra


This is a presentation on towball weight relevant to towing and why advertised GVMs may be misleading . Mainly aimed at 4wd but same rules apply to any vehicle. The embedded video is not relevant other than to show how the police and road authorities weigh your vehicle.

It's interesting to note that they use a Toyota Landcruiser as an example which most people would assume could carry Ayres Rock, well maybe one of the Devils Marbles anyway.

http://rvdaily.com.au/issue015/?utm_sou ... +Send+2#31

This link lists the GVM of most popular vehicles.

http://www.centaurproducts.com.au/filea ... mplete.pdf

At the end of this link there's a few common additions/items and the weight that they contribute to your payload and why it's so easy to unwittingly exceed your GVM.

http://www.4wdingaustralia.com/4x4/what ... 4wd-weigh/
Ozzie
Investigator #143 "SPRITZIG II"

The Mariner - “It’s too strange here. It doesn’t move right." ...
Enola - “Helen said that it’s only land sickness."
Waterworld (1995)
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Ozzie
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Re: Gross Vehicle Mass

Post by Ozzie »

https://www.carsguide.com.au/car-advice ... sted-67029

Top towing myths busted

Thought this link may be of interest as we all tow. The load hitches one is irrelevant on some vehicles such as my Falcon where Ford specifically forbid the use of such devices in the owners manual unless you have the top end tow package/ towbar.

I still have the brackets for sherpards crook shaped weight distribution hitches on the 563 trailer from when I towed it with the Pathfinder and I think they made a difference, they certainly did with my caravan. As the article suggest they are an aid and not a fix all for overloaded towing setups.
Ozzie
Investigator #143 "SPRITZIG II"

The Mariner - “It’s too strange here. It doesn’t move right." ...
Enola - “Helen said that it’s only land sickness."
Waterworld (1995)
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Ozzie
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Re: Gross Vehicle Mass

Post by Ozzie »

I was reading a vehicle review on Pat Callinans 4wd site regarding the Ram 1500 and thought I’d include this screen grab
E9B8FF93-93F1-4E3C-9FED-9CD3673C0803.jpeg
E9B8FF93-93F1-4E3C-9FED-9CD3673C0803.jpeg (21.64 KiB) Viewed 5539 times
When we toured Alaska a few years back these dodge Rams, Toyota Tacomas and Ford F truck behemoth dual cabs were the most ubiquitous cars on the road. Since the end of the local motor industry there seems to be more of them here now . They look like they could tow the Queen Mary but as the above grab indicates, put the full towing capacity on the back of the Ram and it would be illegal for the average front row forward to drive it . This even surprised me and I’m getting used to seeing such articles.

Just FYI :) I doubt anyone will buy one to tow their Investigator, but a good example of why towing limits are misunderstood.
Ozzie
Investigator #143 "SPRITZIG II"

The Mariner - “It’s too strange here. It doesn’t move right." ...
Enola - “Helen said that it’s only land sickness."
Waterworld (1995)
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Andrew
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Re: Gross Vehicle Mass

Post by Andrew »

Gday Ozzie,

Just re adjusting the ball weight (BW) on my trailer, 10% of the ATM of 1200kg, so 120kgs. Its currently at 105kg..so a bit more to tweak. I've moved the axle and could move the winch post to change BW. Using the bathroom scales with 12mm plywood under the jockey wheel.

GVM of the tow vehicle. Should be no worries, its a Totota workmate ute , can carry about 750kgs in tray, only acessory is a back window guard grille.
Andrew

Investigator #9 Teria
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Ozzie
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Re: Gross Vehicle Mass

Post by Ozzie »

Hi Andrew. If you have 105 you could probably fix it with judicious packing in transit. In the early days I had a monster truck battery in the rear locker and with the 5 hp ancient Mariner I could lift the trailer off with one hand . After ditching the battery and packing my heavy stuff in the forwards area I have perfect weight just by removing the outboard. It’s always interesting to check though.

Another interesting point on GVMs for those I have not bored crazy :) , I weighed one of the spare wheels (standard steel/standard tyre) on my Hilux . I was curious as with my deteriorating back I was having trouble lifting it. 30 kg . Not sure how much more they weigh, but when you see 4wds with big Sunraysias and 33inch monster tyres they have substantially added to the extra weight (times four plus number of spares) and as such reduced the spare capacity for load and towing. Even though this is unsprung weight it matters not to your allowed GVM and total combined mass. It’s the whole thing that goes on the weighbridge.
Ozzie
Investigator #143 "SPRITZIG II"

The Mariner - “It’s too strange here. It doesn’t move right." ...
Enola - “Helen said that it’s only land sickness."
Waterworld (1995)
User avatar
Ozzie
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Joined: Wed May 27, 2009 1:07 pm
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Re: Gross Vehicle Mass

Post by Ozzie »

And while we’re on my fav subject just a little snippet on GCM upgrades and how they differ state to state . New GCM (gross Combined Mass) for existing registration vehicles are now banned in some states ( not retrospective). It’s a complicated mine field and as with most of these things in the end the insurance premiums for certification providers and for modified vehicles that make the cost of this stuff astronomical.

https://www.carsales.com.au/editorial/d ... gK2dvD_BwE

I may take up towing a canoe with a bicycle just to be on the safe side :shock: :shock:
Ozzie
Investigator #143 "SPRITZIG II"

The Mariner - “It’s too strange here. It doesn’t move right." ...
Enola - “Helen said that it’s only land sickness."
Waterworld (1995)
User avatar
Andrew
Posts: 541
Joined: Sun Aug 18, 2013 11:33 am
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Re: Gross Vehicle Mass

Post by Andrew »

Got the ball weight to 115kgs, by moving axle and winch post. Thanks for the tip on boat loading, packed my water containers into cabin just foward of axle. (they go in cockpit lockers afloat) Motor always rides in ute. She tows better now without any hobby-horsing. blog update http://teria563.blogspot.com/2019/10/tr ... eight.html

Nice to be back out on the water, after 2 years layup. tho its a bit too windy for comfort out on the paddock. So hanging off the hook near the tsv casino, a safe anchorage in strong E to SE winds. The shakedown sail went well.
Last edited by Andrew on Sat Oct 12, 2019 6:00 pm, edited 1 time in total.
Andrew

Investigator #9 Teria
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Ozzie
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Re: Gross Vehicle Mass

Post by Ozzie »

Fair winds Andrew :)
Ozzie
Investigator #143 "SPRITZIG II"

The Mariner - “It’s too strange here. It doesn’t move right." ...
Enola - “Helen said that it’s only land sickness."
Waterworld (1995)
User avatar
Ozzie
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Joined: Wed May 27, 2009 1:07 pm
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Re: Gross Vehicle Mass

Post by Ozzie »

https://www.thegreynomads.com.au/overloaded/

This story is a tragedy for all concerned and I won’t add anything to it .

There are multiple reports on the net now re overloading and police blitzes on such. Providing your load is balanced, a trip to launch, sail and retrieve should not be an issue, providing your tow vehicle is correct. However, many people are using boats as caravans these days and nothing wrong with that, but it does highlight the problem of taking more stuff than you would normally, tents , bbqs and the like and the problem of overloading or unbalancing. When working out your weights remember a litre of fluid as a general rule weighs a kilogram. Your 9kg gas bottle weighs up to 16kg full. Also, you have to include yourself and your passengers.

For our motorhome I’m buying a set of portable Reich scales to go with my ball weight scale. At $350 not cheap but what’s a life worth.

Edit From Elgas Aus site

“How Much Does a 9kg Gas Bottle Weigh When Full

A 9kg gas bottle weighs 16.3–19.0 kg* when full. The weight variation is in the empty 9kg gas bottle weight, do to manufacturing variances. 9kg refers to the weight of the contents only.”
Ozzie
Investigator #143 "SPRITZIG II"

The Mariner - “It’s too strange here. It doesn’t move right." ...
Enola - “Helen said that it’s only land sickness."
Waterworld (1995)
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