Trailer weight, Towing advice

[blackjack]

hello all
blackjenny here doing the research for blackjack
(i tried to register as a member in my own right, but the email address being the same as jack's, it wouldn't let me)

if you caught jack's first post
http://www.ausfish.com.au/vforum/showthread.php?t=132707&page=3

(don't know if i did that right "seafarer, freedom escape, signature" thread anyway), you'd know we are complete novices to the boating world.

after much research we have found a terrific boat - a seafarer ventura

all the advice we've received is invaluable, as is the advice to others on this site

(i'm actually packing it when we come to launching and retrieving the boat we get for the first time :-/. the ramp etiquette alone and the drive-on, winch-on thing well .... i hate p'ing people off)

anyway, some questions we need your advice with (i'm taking on the research coz jack's too busy)

how can we make sure the weight onto the towbar is at least 10% so we avoid a towing catastrophe eg if it weighs 1400kgs, the weight on the tow bar should be 140 kgs...right?
general tips for towing - only ever towed a box trailer b4. The boat weighs a LOT more obviously. jack is a deft hand at backing the boxy at least
any general test drive tips
is there a way we can tell about the compression of the motor. the current owner is a decent guy seemingly - a genuine chap with a lovely wife and family whom we met. he said he just had a mechanical and compression check 1.5 yrs ago and he's only taken it out 5 times. i believe him. risk i feel we can take.
a dealer told us a 150hp engine will use HEAPS more fuel than the same make/2001 (Evinrude) 115. any comments?about the directed steering thing - the owner says he had it on his boat before. something about a box from the steering wheel that aids with keeping the direction steady???? so maybe if you are going in one curve, it maintains that curve until you change the course. he might have said it kind of 'locks' or 'keeps' you going along your chosen path ???? we will ask more q's when we get there

looking forward to hearing from you guys/gals

jenny :)

[Moonlighter]

Hi Blackjenny

Had a look at Jack's earlier post and the Seafarer Ventura is a very nice boat, so some brief thoughts on your questions:

1. Weight on towbar @10% can be a bit much. 5 - 10% is the guide, but will also greatly depend on your car - most car manufacturer's set a max towbar weight/downforce so you'd best check that out in your owner's manual and make sure you don't go over the manuf recommendations. You do need some definite solid downforce, otherwise the "tail will wag the dog" and you will be in big strife towing it anywhere.

2. If Jack is good at towing and backing a box trailer, he will find the boat generally easier to reverse because being longer they don't react so quickly and so are easier to back in straight lines and slower to respond to the car's steering input. Just remember they are longer and be careful to leave room when doing low speed turns!

3. Test drive tips:
* make sure the boat is easy to launch off the trailer - this indicates a well set up trailer.
* make sure the trailer is rated to carry to overall weight of the boat/motor/trailer, with a couple of hundred kg's margin - worth a quick trip to the weighbridge at the local tip!)
* make sure the motor starts easily and runs well.
* Accelerate gently onto plane, then run at various speeds including full throttle.
* A good procedure used by the better boating magazines is to run at a good fast cruise speed and do a big circle of at least 1km diameter - this means that the boat's performance in all sea directions can be assessed. Then do a slalom run over about a 500m distance and see how it goes.
* The newer Seafarer Ventura's are a well known quality boat so its performance should easily satisfy these tests.
* With 150 hp it should go great. I friend had a Viking with 130hp Yamaha and it went well, I think 115 would be not enough power and you'd have to work the 115 hard to get decent performance out of it.

I reckon an ideal new motor on this hull would be the 140hp Suzuki. The 150 Johnno will be heavy on the fuel, especially so if you drive it hard. Australian Fisherman & Boatowner Magazine has a lot of test data on engines and if you google them I'm pretty sure there is a test of the 150 Johnno including fuel consumption available thru thier website. Be prepared to see some big figures!

4. Test compression. If you are serious, the only sensible thing to do is to get a engine report from a reputable mechanic. If in the Brisbane area, I use a mobile mechanic Jon Eadie (he's an Ausfish member too I think - Jon80) and it would be well worth the money to pay someone like him to run a comp test etc and generally check over the boat for you.

5. The "directed steering" thing - I've not heard of it referred to as that - suspect it may be what's called "NFB" or non-feedback steering and it basically has an extra set of gears that helps take the "torque" steering out of the equation. Torque steering occurs due to the twisting effect of the propellor turning in the water - it makes the motor want to turn in the same direction as the prop and is referred to as "feedback". Its especially noticeable whenthe motor is trimmed all the way in (or down).

The NFB cable steering is better than cable steering without the NFB mechanism, but there is, in my opinion, no substitute for hydraulic steering which is lighter and much easier to use. Hydrive is the Australian made version, which I fitted to my boat a few years ago. Good gear!

Good luck with the new boat!

Grant

[ozscott]

Hi Jenny. I have a 1970s Seafarer Vagabond - 20foot. The bare hull was 800kg without the armour plate screen. Off the trailer, in the water, she would be about 1400kg before people in it, but fuelled up with gear also (I have a lot of extras incuding 2 large batteries - 150litres of fuel etc). I have a 115 93 Yammy 2 stroke V4 - the vs punch above their weight so to speak. The best way to tell if the 115 is right for you is to drive the thing. I thought mine would be underpowered, but it gets out of the hole very quickly and does 62kph on the GPS flat out at 5500rpm - fully laden with 2 large fellas and all the gear and fuel.

As for direct steering Grant has probably nailed it. I installed recently a Telflex NFB steering system - it uses planatery gears and a cam in the helm (the thing behind the dash that the wheel attaches to) and it simulates one of the benefits of hydraulic (lot more expensive) steering - it will not, like most mechanical steering, move the wheel back from the torque of the propellor if you take you hand off the wheel. You can position the wheel and forget it - straight, turn, does not matter.

Cheers

[ozscott]

ps. I agree with Grant about hydraulic, but it is signif' dearer than cable and this particular Teleflex I purchased is very smooth and is finger in the spoke turn from lock to lock - albeit its not as light as hydraulic. Further if you go much more than 140-150hp hydraulic is recommended anyway given the weight of the motor.

PPS. I have had 5 adults and kids in mine in calm water and it still pulls hard.

Cheers

[ozscott]

Jenny - to get extra weight over the tow bar (you can check this with a solid set of bathroom scales and a board to sit the jockey wheel of the trailer on) you need to slide the boat forward on the trailer. This is usually done by moving the winch post forwards towards the car ...but you will need to have regard to where the rollers are sitting - it might require all of them to be moved etc...ask a trailer fellow about it.

Cheers

[Chimo]

Hi Jack and Jenny

Just another quick comment re your trailer.
Specially balanced on the trailer to take the weight off the towbar - can lift the boat up easily by myself

I suggest you heed the comments about the risk to your safe towing activity if there is so little weight on the front of the trailer.

Dont exceed the down force weight specified for your vehicle towbar set up tho.

Finally perhaps, as you suggest you have a good relationship with the vendor, why dont you ask exactly what was involved to achieve the

"Specially balanced on the trailer to take the weight off the towbar"

If it was; as Ozscott more than likely correctly suggested; a change in the position of the winch post, you may be able to see some marks on the trailer that indicate where it was originally. Mayfair who make Tinka trailers and set them up for Seafarers have done it for years and probably know what they are doing by now so returning the winch post to where it was would likely be a good place to start.

Cheers
Chimo

[FNQCairns]

You manufacturer/towbar maker will specifythe tow bar weight limit, The 10% rule is not an absolute but it does help, just a guess but If I remember correctly you had a mid sized car 140kg hanging from the towbar might see you spotting Koalas??

Oh on the 115 and 150hp thing, the 150 will be spinning slow compared to the 115 at the same speed so with an eye toward economy but still getting to the desination in good time the gap between the two in fuel use narrows a LOT!

cheers fnq

[Kleyny]

what sort of car do you have?
90% of towbars have their ball weight on a plate spot welded onto the bar some where. Unfortunately sometimes this can be covered by a bumper bar. but just have a good look before trying anything else in regards to what the downward max weight is.

If you don't have a set of scales that go that high go down to your local public weigh bridge and weight the whole unit (i suggest you do this anyway so you know exactly what the whole shebang weighs "fully loaded")
Once you get the whole weight just nudge the jockey wheel of the bridge and take that reading.
subtract that reading with your first one and thats your ball weight. I'm sure if its too much the weigh bridge person will let you play with it on the bridge if they aren't too busy.
IMO the 150 might use a little more go go juice as FNQ has said but i would rather have too much than not enough.
neil

[blackjack]

Grant - Mate - thanks for the extensive info - you obviously have plenty of boating experience. Getting the boat back from Sydney is a bit of a worry. The owner has the weight distribution set up for his CRV with urban speed in mind - which is what we want as well at Tea Gardens .... but (2006 Honda same as mine) we need to get her up the ventura highway from Sydney to Newy. I've decided to ask him to move the weight forward as I'm not prepared to see my new boat beside me at 100k on the freeway :o Will look at redistribution of weight when I get her home if needed. I'm prepared to get an old Cruiser or similar for $5K just to pull her around if the CRV struggles. Jeez we are only gonna be 200metres from the boat ramps.. surely the Honda can handle that. :-/ The motor is OK will sus that on the test run. Not worried about fuel costs prefer to have the power if needed - I'm not a revhead so not gonna work the motor too hard. Also will be very tuned into the directed steering cause the test run with standard mechanical was a real eye opener - the missus just about lost it into an endless turn going with the prop rotation - not good. (on a different boat - a Viking with mechanical steering we tested on Wed) I've only handled a boat a half dozen times - I'm obviously no expert so the better steering should be noticeable - I hope:-/

ozscott - Yeah the trailer issue should be OK i think - we can sort that out after we get the boat home. Gonna move the weight forward for the trip & will fine tune it later. Mate we've got a 150 on her so lookin good for the power if needed.

chimo - good advice re the trailer mate - will talk to the vendor about the weight distribution. I'm definitely confused about what to do - sounds like he's set up nicely for the same car that we drive around town & the local boat ramps but towing up the freeway is a problem. As I've said I'm gonna move the load forward for the trip home then fine tune. Did you check the steering answers? Grant and ozscott have done a great job of putting into words what I understand 'directed steering' to be.

fnq - the petrol cost compared to having a great day out with the guts I may or may not need, well as I said I rather have too much than not enough.

Honky - it won't be possible at least when we go down to Sydney to check the weight all up. Have to wait for that 'til we get home and then go to the tip. Have checked the manual and I now know the tow bar can take a safe max. of 120 kgs. Will tow the boat home as empty as possible. Should only be around 1300kgs.

Thanks for the excellent info. Keep you posted. Jack (and Jenny)

[ozscott]

no worries mate - I dont know if this is teaching you to such eggs or not but keep the speed down and the load forward (as you say) and if she does start to swing out and back again accelerate gently, dont hit the brakes...and then after you iron her out, slow very gently down slow enough that she wont do it...

Cheers

[blackjack]

no worries mate - I dont know if this is teaching you to such eggs or not but keep the speed down and the load forward (as you say) and if she does start to swing out and back again accelerate gently, dont hit the brakes...and then after you iron her out, slow very gently down slow enough that she wont do it...

Cheers

Nah. I'm happy to hear advice. I'm a scientist who studies bacteria and viruses infecting humans. It's a l o n g way from this interesting boatie and fishy stuff.

And as a fisherman I make a great scientist.

Jack

[Outsider1]

Hi Jenny and Jack,

lots of good advice in the replies so I will try to not repeat too much of what has already been said.

Firstly on the steering, I have had all 3 systems on my boat; I started with cable, then upgrades to NFB some years later when the cable gave it up, and then I upgraded to Hydraulic when I recently upgraded my motor.

A case of Good, Better, Best. The NFB would be needed with the 150hp motor, plenty of Prop Torque there! Approximately equal steps up in performance in my experience.

NFB, as the name implies, takes out the kick back from the motor but still a little heavy to use. Hydraulic removes the kick back and also gives you finger tip control!, very light and easy to turn the wheel. But Hydraulic is pricey, well over $1,000 fitted for a good system.

Here is a link to a test worth reading of the Viking and the Ventura, side by side. The Ventura as you know is the half cabin version. You will see in the test that it weighs about 50kg more than the Viking.

http://www.boatpoint.com.au/boat-review/2119346.aspx

The 115hp Evinrude was/is an ideal match with the Viking, though even the 90hp Evinrude gets it along quite OK. The 150hp Johnson will be a great performer and won't be too heavy or over-powerful on the Ventura. As long as you are sensible it won't send you broke either on fuel useage.

I actually had a Johnson 150hp on my boat for over 10 years without problems and I kept detailed fuel logs on it. My boat is a Cruise Craft and a bit longer and heavier than the Ventura. The Johnson has plenty of power and wasn't overly thirsty if you kept your cruise to 4,000 to 4,500 rpms which was good for 20 to 25 knots in most conditions. Over some 400+ motor hours my average fuel useage was just over 12 litres per hour of running time.

At cruise of 4,000 to 4,500 rpms I would reckon it would use around 25 litres an hour if it is reasonably set up. It will be an effortless performer on the smaller Ventura hull which will handle it no problems. The Johnson 150hp is a 60 degree V6, nice and narrow profile, plenty of engine displacement and a smoothy as a 6 cylinder. The 150 is basically the same motor as the Johnson 175hp also so it is quite understressed. Have it serviced as per the manual and it will last for years and many hours of use. You won't wear it out, corrosion will kill it first! The only downside is 2 stroke oil smell.

Hope that helps.

Cheers

Dave

[blackjack]

:thumbsup: Sure helps Dave.

Thanks for that link. Interesting article that relates our hull. (at least when we get her)


It's good to know the motor and hull are a good match for each other. The economy looks promising - not a rev head.

Hydraulic steering is something for the future. Along with an electric anchor winch and a second marine battery. New toys to put the pennies into the piggy bank for.

Thanks to this forum, I now have at least the basics of the different types of steering. :P

[ozscott]

Mate - your going to love it.

BTW - keep up the good work so that bacteria doesnt eat us all...I think the human race would like to fish for a few more years yet!

Cheers

[blackjack]

Jenny - to get extra weight over the tow bar (you can check this with a solid set of bathroom scales and a board to sit the jockey wheel of the trailer on) you need to slide the boat forward on the trailer. This is usually done by moving the winch post forwards towards the car ...but you will need to have regard to where the rollers are sitting - it might require all of them to be moved etc...ask a trailer fellow about it.

Cheers

Thanks for that very practical and portable suggestion oz. Will also check on the winch post. Have spoken to the seller, and he's gonna adjust the weight for me before I go down to collect her. ;)



ps. both Jenny and I are bug people. The only thing we might be able to help with on here is info about the infections people get from fishing injuries etc. Nasty. >:(

[Chimo]

Hi Jack and Jen

Possibly this is the wrong thread BUT

Why does a mixture of thirds metho, baby oil and detol with a few drops of tea tree oil work so well to prevent infections from fish hooks and fish barbs while boating and although not strictly your field why does the same mix work as a repellant for midges too?

Cheers
Chimo

[blackjack]

hello Chimo

blackjenny here

i haven’t heard of that combination before, but this is my best educated guess

this link is a very extensive scientific analysis of the reasons tea tree oil (TTO) works, how it works etc.
http://cmr.asm.org/cgi/content/full/19/1/50 (http://cmr.asm.org/cgi/content/full/19/1/50)

just scroll thru it and read the bits that make sense

as you are no doubt aware, the medical world needs a helping hand with the nasty antibiotic resistant bugs we are growing these days.

seems the aboriginal population had the handle on this LONG ago. what’s old is new again???

chloroxylenol is the main active ingredient of Dettol, belongs to the phenol group of chemicals (old-fashioned hospital smell) and is mainly used in medicine as an antibacterial and anaesthetic which kills bacteria, reduces inflammation and relieves itching, redness or pain in skin infections and conditions. it has very good action against many Streptococci (like the golden staph you hear so much about these days). streps are everywhere around us and are quite resistant to salt water. they exist in huge numbers in our gut, the guts of animals, fish, prawns etc. yea and some are much more toxic than others.

mossies and other bugs hate the smell of dettol, so they tend to fly off before they bite you. I’m thinking the baby oil plays the part of making it smell nicer, (no smelly fishermen here – puts a whole new meaning into the word SNAG!!!) it makes the lotion easier to spread, and helps to keep the skin soft and moisturised, protection from wind and dehydration, skin cracks etc. the bite parts of the sandfly may not be able to penetrate thru’ the layer too. not sure. the oil also helps to dilute the concentration of dettol, which burns if it’s too concentrated and the metho which tends to dry the skin out too much

metho is better as an antibacterial agent when it is diluted, in fact much better than 100%. It is cheap and kills just about everything.

i’ll need to make some of this stuff up to put in our new boat because all up it seems to address the combo of bugs as microscopic and biting. is it in the recipe section of the forum? just a thought

cheers

thanks for the question. i learnt. jen :scholar:

[Outsider1]

Very interesting Jenny, thanks for posting that info.

Dettol kills Cane Toads very effectively too. Just spray it on them and they cactus in within a few minutes.

Cheer

Dave

[Chimo]

Hi Jen

I knew the mix works in a range of situations even without the Tea tree oil and it good to have your input on it too.

Its a good brew to have around to cope with the insects as well as the hook scratches and pricks as well as the impact of fish spines.

I use Tea tree oil in the 100% conc. for any midge or mossie bite I get when I have failed to apply repellant.

Another question for you and Jack. (Maybe we need a Granny's Cures and how and why they work thread too).

Why when you are spiked by a flathead can you cure the pain by inserting the spiked finger into the stomach juices of the offendinge flathead or its cousin for that matter?

Cheers
Chimo

[Mindi]

one thing which may have been mentioned but I didnt see...and it's important...when driving with a heavy towed load leave heaps of space in front of you to stop...yes...idiots will overtake you and jump into the gap all the time..welcome to towing a boat. This is IMHO the most important safe towing factor after having the weight set up so that the load does not sway. ...Just keep "dropping back" to maintain a gap. You may well manage to maintain your boat trailer brakes better than most of us..but the best strategy is to never need to find out...Speed is the real enemy with this sort of towing, or more particularly wiping it off.

[blackjack]

Hi Jen

Another question for you and Jack. (Maybe we need a Granny's Cures and how and why they work thread too).

Why when you are spiked by a flathead can you cure the pain by inserting the spiked finger into the stomach juices of the offendinge flathead or its cousin for that matter?

Cheers
Chimo

blackjenny reporting

no expert on this at all chimo, but my best answer is because of the alkaline nature of the stomach slime proteins (edited, had it round the wrong way before) 'denaturing' the acid components of the spike poison literally changing their nature and rendering them to a new makeup. an actual chemical reaction takes place between the protein and the acid. the basis of hot water treatment (treatment of choice) is similar. the heat denatures the acid protein of the poison, is heat labile. but you don't usually have hot water to hand. :'( (even fresh body temp urine may help if nothing else available - it's sterile too)


from what i have gathered since i first posted this answer:

the spike poison is acidic, maybe pH 4.0
the belly slime is more alkaline, maybe around pH 7.0-8.0
(saltwater also is pH around 8.0)

acid + alkali = neutral

interesting also slime contains enzymes and has antibacterial properties that help protect the skin of the fish


if the injury is penetrating in any real depth, you'd need to try and get the acids and the alkalis to contact each other too i'd imagine. maybe the salty slime water can penetrate. at least you've got the fish at hand, so to speak, so the first aid is there ready to try

http://www.nola.com/sports/t-p/index.ssf?/base/sports-35/1202019674247260.xml&coll=1 - an interesting link about medical properties of fish slime


i can never forget being with my darling Daddy one day when i was about 7 years old. he was spiked by something when he was digging around in the contents of seaweed from a hand prawning net in Lake Macquarie, NSW


it was called a bull rout


anyway, my dad was a tough guy and to see the pain he suffered was just awful. he wanted mum to cut his arm off!


this is a really useful page of first aid for the outdoors, simple and practical advice

http://www.parasolemt.com.au/venum.asp (http://www.parasolemt.com.au/venum.asp)


maybe i'll print it off and laminate it for the boat? anyway guys, (and I mean gals too whenever I say that) i cannot stress enough just how CRITICAL it is to get some antiseptic cream, lotion or even basic soap and water wash on ANY cut big or small, that breaks through the integrity of your skin, especially if it draws blood. and i am as serious as death about what can happen if you don't. :bomb: (from secondary infection) make sure your tetanus cover is up-to-date too, c'mon guys MAN TF UP


also, there is a range of waterless handwashes available now in plastic pump packs, like Aquim, which you can put in your boat and have readily accessible. use it anytime you need to wash your hands.


off the track i know, but just thinking about my Dad...lost him 10 yrs ago, only 59


he always had boats, sailing and power and i have my love of the water and boating from him. i sailed too, sabots, vee jays and a northbridge senior. we skiied all over the lake, and he taught me how to catch fish, and crabs and prawns. he took me outside fishing too. so it's not just you guys who inherit things "blokey" from their old man. i've read plenty of things about men and their dads on here, men and their sons. (not saying you) so i'm just addressing a bit of the imbalance


so you can imagine, i am just about out of my skin with excitement about getting our first boat since marrying jack 25 yrs ago!!! (best anniversary present ever) this wednesday if the test run works out. :2vrolijk_08: i cannot wait!


thanks for the question. i learnt something new. :scholar:

jenny


p.s. i am often telling my daughters liz and cath, "if you don't learn something new, every day, you might as well give up!"

[blackjack]

one thing which may have been mentioned but I didnt see...and it's important...when driving with a heavy towed load leave heaps of space in front of you to stop...yes...idiots will overtake you and jump into the gap all the time..welcome to towing a boat. This is IMHO the most important safe towing factor after having the weight set up so that the load does not sway. ...Just keep "dropping back" to maintain a gap. You may well manage to maintain your boat trailer brakes better than most of us..but the best strategy is to never need to find out...Speed is the real enemy with this sort of towing, or more particularly wiping it off.

thanks mindi

we will be mindful of that good advice. not only does it sound safer to allow for the d'heads, it will save on the juice bill.

after waiting soooooo long to have a boat, i'm not prepared to let it get damaged! :rifle:

cheers, jenny

[skipalong]

go the big one fort sure

[seatime]

From http://www.caravanandcampingsa.com.au/page.asp?parentid=22&parent2id=96

Towing Weights
In 1989 Australian Design Rules (ADRs) were introduced which affect the construction and towing of trailers, including caravans. Currently there are no towing regulations which specifically refer to ‘caravans’. The ADRs include the requirement for plates on trailer drawbars which amongst other information states the aggregate, or maximum, mass of the trailer and data on the towbar which indicates the rating of that towbar. It should be noted that ADR 62 states that the rated capacity of the towbar …. “shall not exceed the vehicle manufacturer’s recommendations”. Below is a summary of the rules relating to towing weights which should assist in the selection of towing equipment and/or caravan and the towing speeds applicable to various states.
While there are some variations in the Road Traffic Regulations in different States, most agree on the following safety aspects:
The trailer must not be bigger or heavier than the driver can safely control,
The total or laden mass of the trailer must not be more than:

- the maximum mass (A.T.M.) determined by the trailer manufacturer and as stated on the trailer plate,
- the load rating of the trailer’s coupling of the towbar fitted to the towing vehicle,
- the total load rating of all the trailer’s tyres.The combination of tow vehicle and trailer must be “properly set up”. This means that there is a load of about 10% of the total trailer mass on the towbar and that the outfit has a level attitude. Generally this necessitates the use of a load distributing device.


Exceeding the maximum towing load as recommended by the towing vehicle manufacturer can:

Invalidate warranty
Nulify insurance, and
Effect long term vehicle safety and reliability.National Towing Regulations
In December, 1998, agreement was reached by all State’s Ministers of Transport to implement National towing regulations.
In essence, the National rules state that “A motor vehicle with a Gross Vehicle Mass (G.M.V.) not exceeding 4.5 tonnes must not, without the approval of an authority, tow a trailer with a mass (including any load) exceeding;
The capacity of the towing apparatus fitted to the vehicle, or
A relevant maximum trailer mass specified by the vehicle manufacturer.”
Put simply, the most you can tow is the amount specified by the vehicle manufacturer of the capacity of the towbar - WHICH EVER IS LEAST.
If you want to know how much your vehicle can tow, firstly check the owners manual or vehicle sales brochure for the manufacturer’s towing recommendations. Secondly make sure that the towing capacity is as least as much, if not more, than the mass of the trailer, including its load. If you are unsure how strong the towbar is, have a chat to a reputable towing equipment specialist.
In the case where a motor vehicle manufacturer has not specified a maximum towing mass, the limit is stated to be:
1.5 times the unladen or herb mass of the motor vehicle if the trailer is fitted with brakes; or
The unloaded mass of the motor vehicle if the trailer is not fitted with brakes.
It should be noted, however, that the above will rarely apply as apart from using a truck, just about every vehicle that is likely to be used for towing a caravan, boat trailer, horsefloat or similar has a manufacturer’s towing recommendation.
Owners of 4WDs and light commercial vehicles should also be careful that they do not exceed the Gross Combined Mass (G.C.M.) of the vehicle. The GCM refers to the maximum vehicle plus its load, including a trailer, is permitted to weigh. It is possible that when a motor vehicle is loaded with, for example, five adults, their luggage and camping gear that the maximum allowable trailer mass has to be reduced so as to not exceed the GCM.
While this may sound a little confusing, it is important that this is considered so as to not void the warranty or insurance.

[Razgo-]

I just had a heavy duty Hayman Reese tow bar fitted to my tarago(1.8tonne vehicle) and they said max weight on all cars was 750KG and then after that you needed electric breaks on the trailer. the Hayman Reese heavy duty will go to 1600KG under electric breaks.

that was from speedy exhausts who do mobile towbar fittings.