View Full Version : Trailer axle load & GVM, 5.5m boat

01-08-2010, 04:09 PM
Hi Guys,
I have a 5.5m glass boat with 200L fuel capacity & was concerned about trailer axle load, so I weighed the axle fully loaded & it has raised some issues. Axle load is 1600kg fully loaded with everything, fuel, ice, fishing gear ect. & GVM is 1795kg's & tow ball weight is 195kg's. The trailer used to be a tandem but previous owner removed tandem axles & put in a single axle for ease of moving trailer around yard. The axle is a 45mm square with Ford SL bearings with 45mm x 8mm 6 leaf gal springs. I tow the boat only 50km to my local ramp but travel 150km now & again also. I know the axle is rated to 1500kg's & springs I think are close to that also. Are most 5.5m boats on single or tandem axle trailers.

I am interested in what boat size or weight others & putting on there single axle trailers & if I am pushing the envelope & asking for trouble i.e. possible bearing/axle failure. I pulled the hubs apart today after 12 months & hubs are perfect with fresh grease in both inner & outer bearings. I assume all axle failures are from bearing failures??

Should I put a tandem setup back on? Just put a lazy axle behind the current one with everything rated the same with slipper springs?

Interested in your thoughts.


Why Not
01-08-2010, 04:19 PM
I'd be interested to know what is on your trailer compliance plate. If the previous owner modified it he should have had it re-stamped. Not trying to get on a high horse. Just be aware of your insurance obligations. Most insurance companies would drop you like a hot potatoe if they could.

Why Not

01-08-2010, 05:03 PM
When I looked around recently the heaviest gal springs I could get were rated to 1200kgs, and I am using a 45 square axle too. I recon mine is borderline and should be a bit lighter than yours. I think the springs are the biggest issue from what I can see, the towball weight sounds a bit heavy too although I am not an expert so please wait and see what the others say about that one.

01-08-2010, 05:36 PM
It is a dumbier trailer originally but new compliance plate was fitted when axle changed. Compliance plate shows 1500kg axle class, 360kg Tare Weight & 1600kg GVM. When only main fuel tank is full the axle load is 1500kg's with 1600kg GVM so just within compliance plate specs. The issue is when boat is fully fueled, ice & fishing gear it exceeds the compliance plate for axle load & trailer GVM. I see tandem specs for Dumbier trailer is 2000kg GVM. My GVM fully loaded is 1750kg & not 1795kg's as previously stated. If I add another axle then this will also increase the GVM by approx. 60-80kg.s so fully loaded I would be approx. 20-30kg's over my max legal tow weight for Hilux. I think I can get this weight below my max. tow weight of 1800kg's for the hilux though. Yes tow ball weight is high. I can adjust this but it will put more load on the single axle. Starting to think tandem is the way to go$$$$$

01-08-2010, 05:38 PM
Tinshack it's hard to get a single axle trailer to rate above 1500kg, check your tyre's weight rating too.

others may know better but i suspect your stuffed and illegal, if you must stay with single look toward a landcruiser/patrol rims and tyres/bearings/stub axles/axle otherwise you need to go back up to twins.

White Pointer
01-08-2010, 06:10 PM

Based on your weigh in and the trailer ratings you are 195Kg overweight fully fuelled and loaded.

Do you know where the discarded axle is? If so, put it back, quick.


White Pointer

Daisy Burnett
02-08-2010, 04:42 PM
Tow ball weight I am told should be 10% of the total boat weight. At least that it what Dunbier told me when I asked about my new trailer.


02-08-2010, 08:28 PM
hi mate, my trailer is single axle homemade by me, its rated at 1800 kgsfor this you need 50mm axle and tire rating, i dont have landcruser or hilux rims i have falcon mags 15", you can download specs for trailers from the department of transport site.

03-08-2010, 12:11 PM
Can get 1650kg with H/D tyres and 50mm axle , 10 leaf gal springs. Tow ball weight 7-10% of ATM.
Ring Dunbier.

06-08-2010, 07:56 PM
Thanks guys, I have researched & have decided on the following;

The highest rating you can get for a single axle using 45mm square axle & Ford SL bearings is 1500kg. Can get 2000kg rated axle using parallel bearings but need to get new rims as brake disc's are bigger & can't get galvanised hubs ect..

Have decided to go slipper tandem, 1500kg rated axles with SL ford bearings, 1200kg rated spring sets, gal hubs. Axle set will be rated to 2400kg's with 2000kg's GVM. Cost is approx. $1200 doing all the work myself, reuse existing axle as front braked axle & install new lazy axle at rear.

Best outcome, peace of mind when towing long distance.

Thanks for your input.:)

06-08-2010, 10:20 PM
tin, max tow ball weight rating is stamped on your towbar,i would say 80-100 kg ball weight should do it as this is all positive weight on the ball.