Securing methods for boat onto trailer for travelling

[Pirate Pete]

Was curious what the consensus is for securing a plate boat onto a trailer to travel over corrugated roads. I use 2 rachet straps, one on each back corner and a turnbuckle on the front, instead of the chain supplied on most trailers. My theory is to make it one rigid piece and not allow the boat much, if any, movement.

Should some movement be allowed. Also the trailer has 9 or 10 keel rollers plus about a 5 - 6 foot skid on each side.

[wayno60]

Lock it down tight and let the springs do their job..

[Apollo]

Agree with Wayno. We use to tow sailboats all around the country and only saw one damaged. It wasn't strapped down well. In areas that were known to be a long drive over rough roads, we use to jack the boat up and place compressed close cell foam between the boat and slides, but I don't think that is warranted on a platey.

Where you going?????? Huh? How to read a good report!

[PADDLES]

i've been told by the boat shop that hog tying them down is the go (they said the insurance data indicates this is the method with least damage in a prang). big strap straight over the gunwhales down the back. apparently it allows less movement (front/rear) in an accident than transom straps if your winch post fails.

[Pirate Pete]

Where you going?????? Huh? How to read a good report!

Looking at going part of the way up the cape next year, so preparations are underway to make it suitable for long distance travel on rough roads. I also go locally (about 4 hrs away) where there is about 1 1/2 hours of gravel, corrugations, cattle grids, potholes etc etc.

[oldboot]

What ever you do, do not rely on the winch post, there are all to many instances of winch post failure, ya just have to look at all the pictures ya see posted with this particular failure.

Anything that moves arround on a trailer is going to get damaged one way or another.

Have a look at the National transport "load restraint guide" ( google will find it), and it will show you the minimum requirements.

Its a good read, and it raises a number if issues, you may not have thaught about.


Breifly
Minimum you must provide resraint as a persentage of the loads mass, to prevent movement in that direction.
80% forward
50% sideways
50% to the rear
20% upward

and that is an expectation for a relativly smooth road and to prevent loss of the load not movement that may cause damage.

remember you can not rely on any friction on a boat trailer and many of the lashings we use do not act directly so their lashing capaity has to be worked out...... those straps may easily be overloaded

So many boats we see being dragged arround rely on the winch strap and a single strap over the thwarts......anybody who has thaught about it will realise that this is hoplessly inadequate.

remember each end of the boat has to be held down seperately and if the thwart strap fails to do its job the boat can simply ride up over the winch post unless the front is held down and secured toward the rear.

Remember too that trailer flex, some quite a lot......ya need the boat tied down to the trailer so the whole thing rides a 1 rigid mass.

cheers

[jason p]

i do agree that you should have it secured down tight but just enough so there is no movement, not cranked down with all your might.

sorry off topic but wayno60 that pic is wrooong in a very huge way:helpa:.
mate your other 1 didnt hurt the eyes, just did the brain in lol ;D.

jp

[Fed]

Minimum you must provide resraint as a persentage of the loads mass, to prevent movement in that direction.
80% forward
50% sideways
50% to the rear
20% upward
I think most trailer winch posts and a rear tie down would fit into those numbers Oldboot.
70726

[oldboot]

Obvoulsy lots of trailer winch posts do not.....note that most well informed (particularly large)boat owners chain the front of their boats down and back independent of the winch post.

Consider that most winch pots are held down with mild steel U bolts of uncertain heritage and only 1 of those u bolts will be doing a danm thing in either forward or rear directions.

Then consider that the winch post provides considerable leverage.

So the considered safe tensile strength of a good quality 1/2 inch mild steel bolt is arround 300 KG.. how does that leave your small half tonne boat, once the leverage of the winch post is considered.... that does not account for corrosion or stress points introduced by the method of bending.

now lets think about those rear straps.......if they run in a straight line in the rear direction from the attachment point on the trailer to the attachment point on the boat, they will yeild 100% of their strength.

BUT..if they are at an angle the load capaity reduces with angle..at 45% the load capacity is reduced to 70%.....so if you are using the typical 1" auto shop webbing that rates at arround 320KG..that wont be enough for a 1 tonne boat for the rearward component.
If the angle opens up to 60% it wont be sufficient for a 1/2 tonne boat.

The "she'll be right" mentality is why there are so many instances of boats comming off trailers.

The only reasons why there are not more boats comming of trailers is that the majority only get out a couple of times a year and even then they don't travel far.

cheers

[tunaticer]

The pros at Stanage bay use poly pipe on top of thier skids as it provides enough cushioning and support for the boat without damages. I converted mine over to poly pipe a decade ago and its been sweet since. Long running boards with 40mm poly pipe screwed to the top of the boards.

[robothefisho]

So the considered safe tensile strength of a good quality 1/2 inch mild steel bolt is arround 300 KG..


When did bolts become that weak?

[oldboot]

When did bolts become that weak?

If you disagree, show some figures and then account for a safety factor.

There is no point just saying its strong enough.

lets talk minimum breaking strain plus a safety factor of at least 4, that is what they will ask you in court when your boat comes off and kills a family in an oncomming car.

What is the minimum breaking strain and what safety factor was used.

My figures may be conservative, but show me better.

Now it is all about knowing what the components are good for..this is why even the cheapest ratchet straps have load ratings on them.

cheers

[oldboot]

Ok some further information about this whole bolt strength thing.

from here http://www.misumiusa.com/CategoryImages/Metric_2006_pdf/METRIC1847-1848.pdf

we find that the yeild strength of a 8.8 high tensile m12x1.75 ( close enough to 1/2 inch) bolt is arround 5500KG....that is the strenght that it starts to stretch at.

8.8 or grade 8, similar will be arround twice as strong as low or medium carbon steel so arround 2250KG.
that is for a good quality bolt. that realy isn't mild steel.

apply a safety factor of 5 recomended for repeated pulsating loads..450KG

Now who knows what steel the "U"bolts are made off AND consider the threads are mostly rolled not cut and thus are not full depth and not all that strong...so the 300KG aint all that unrealistic, particularly if you calculate from "proof load" (the strength before the bolt starts to stretch).

cheers

[cormorant]

I would ask the builder of the boat if it is a recent build. They may suggest extra tie down lugs to be welded low on the hull or where and how much tension/ support is required if straping over the top. Boats were never designed to be strapped down super hard to a flexible crap suspension trailer with no shocks at 120k/h over dips and corrergations.

A while ago there was a thread on someone building or preparing a trailer for corregations and offroad. Everything from locknutting, loktite , nylocking, overspecifying gear, stone protection, dust protection for motor, tyre pressures etc. Using rated turnbuckles is fine but it must be wired / locked so they can't work undone just like any trucky does and running a chain both forward and back is obvious as winch posts unless designed for it are not really up to it long term in a lot of trailer designs. Double strapping with extra wide straps firmly spreading the load and stress over many points would be obvious

Supporting the boat. Depends how big, how much flex in the trailer, construction of boat how fast you travel etc. Friend on a 5m boat used single length of hardwood over the keel rollers routered so it locked in keel and rollers and with the extra height that gave them made extra long extra wide bunk supports that clipped over the existing ones and were rubberised. This allowed the boat to be firmly strapped down with extra load in it ( think about your total weights) , some flex in the trailer and when the long legs are over just a deep launch and remove the wood until required again. He had done it before and without the wood he stuffed rollers and had marks where the bunks were from where he hogtied it down too hard. He had lights vibrate off , light cable wear through and even towbar bolts loosen up and saw others with broken engine mount brackets.

Have to say the speed you travel at makes a huge difference and the quality of stuff you start with. Somehow 25 years ago we travelled terrible roads , overloaded, with thin boats on crap trailers at a reasonable speed ( slow compared to these days) and had little damage but then everything must happen faster these days but we knew the limitations of our gear and the fact we had to fix it ourselves , no real insurance or support always put a dampner on overexuberance ( most of the time).

Strapping anything not designed to be strapped super tight is asking for trouble and stress in a hull, same issue with letting it float and rub long term is no good.

[PADDLES]

top tip about the poly pipe TT, that's a gem i reckon. it gives a nice slidy surface and also a bit of flex/give, brilliant.

[terryc]

Not wanting to frighten everybody but i had the stainless steel u bolt at the front of a 1999 Cruisecraft. snap off at the hull, some how rusted inside outside looked good, was lucky i had the strap over the whole rig which kept the boat on the trailer.

[robothefisho]

Breaking strain of an 8.8/S 12mm bolt would be around 9.5 tons.
Pretty irrelevant though, Consider a winch post is normally held on by 2 ½ inch U bolts. The breaking strain of a U bolt would be around 126*200(crap steel)/9.8= 2585kg*2 (2 shafts) *.7 (a guess at a reduction factor for a U bolt) so 3600 ish kg. Now a reduction factor of 5 wouldn’t ever be applied to it in the design of a winch post. If a winch post was in fact ever designed.
Aside from that though the bolts aren’t directly loaded. As the winch post has a base plate on it, which it trys to pivot on. In real life I’d hazard a guess that the winch post would simply fold over due to buckling or the failure of the welds holding it to the base plate and the boat would continue forward.
One day I might get bored and work out a theoretical failure loading of a winch post but I doubt it.

The whole securing of a boat to a trailer argument will continue forever and is pretty pointless as the securing points aren’t certified. The straps most people use are rated around 250kg. The majority of boats are only snugly secured by the winch cable.

I spose at the end of the day, people should secure them as best they can, because if you were to secure them 100% legally it would probably cost 5 grand.
I don’t have a she’ll be right mentality but a lot of people do and these are the ones that come unstuck. But a boat will never be secured 100% to the letter of the law on a trailer.

[oldboot]

But a boat will never be secured 100% to the letter of the law on a trailer.

Sorry but I think that is a load of rubbish...and that is the line lots of truckies who don't like the current performance standards are pushing too..... but there are plenty of those guys getting fined every day

securing the bow of the boat, independent of the winch post goes a very long way to properly securing a boat.

The two biggest chalenges are the forward and rearward components..a good heavy chain and turnbuckle arrangement fixing the bow both forward and rearward and as a by product down. will do that..and all those components can be obtained in rated form easily and economicaly.

The biggest sticking point is the strength of the eye on the front of the boat..on an alloy boat that is easily fixed.

There is a real issue of putting too much stress on the gunwals of most boats and the structure of the boat was never designed to take a heavy downward force on the gunwals.

But the over straps do not need to be very tight if you are not trying to hold the boat on fore and aft with them... by relying on friction which is in short supply.

Yeh the other thing is securing with the winch rope......in no other situation is it permissable to secure a load onto a vehicle with a winch rope....the winch is an aid to loading and not tie down..and the safety chain on the winch post is only there to stop the boat falling off on the ramp when all the tie downs are removed.

Realy the expectations of securing boats onto trailers need to be improved..don't worry sometime soon they'll run some sort of blitz.

Just like they did on all round white lights.....

All it will take is for some relative of a politician to have a close call with an inadequately secured boat.

cheers

[PinHead]

I just make sure the winch strap is tight and the safety chain is short. Put a decent qulaity strap over the stern and all is good.

[Feral]

Hit a tree with the boat on board last year. (4.9m, with 200 kilo's of batteries on board)
2 of my batteries popped in the boat (Held in with 3x2 timber)
The arse end of the car was twisted and the tow bar pushed in to the body mount points enough to see ripples.
The car was a right off. Tree was embeded about 50cm into the engine bay.

The winch post was bent forward about 50mm, with a slight bend of the post, and the mount plate quite twisted. Boat was fine. No discernible stress on the 50mm strap over the rear of the boat. It was safe enough to just put trailer on to mates car and tow it home.

Winch post was 75mm rhs. Base plate 3/8 steel. All much heavier than than normal trailer fittings. I reckon if I had a standard winch post I would have had a boat mounted in the back of my head. The winch post was held on with standard u bolts. They were bent, but still holding.

[ozscott]

Im with PH. A very hd rear strap. Large 4wd winch with heavy cable and then 2 safety chains - one on bottom of post and another on the gooseneck itself. Sure the unbolt in the bow might be the weak point of all that but it's as good as can be practically achieved.

CheerS

[oldboot]

Hit a tree with the boat on board last year. (4.9m, with 200 kilo's of batteries on board)
2 of my batteries popped in the boat (Held in with 3x2 timber)
The arse end of the car was twisted and the tow bar pushed in to the body mount points enough to see ripples.
The car was a right off. Tree was embeded about 50cm into the engine bay.

The winch post was bent forward about 50mm, with a slight bend of the post, and the mount plate quite twisted. Boat was fine. No discernible stress on the 50mm strap over the rear of the boat. It was safe enough to just put trailer on to mates car and tow it home.

Winch post was 75mm rhs. Base plate 3/8 steel. All much heavier than than normal trailer fittings. I reckon if I had a standard winch post I would have had a boat mounted in the back of my head. The winch post was held on with standard u bolts. They were bent, but still holding.

Yeh but when you say standard "U" bolts.....ya mean decent quality ones or cheap chinese crackers.

Ive seen some good "U" bolts that show little or no deformation where they are bent and good, clean, die cut, full depth threads and have a chance of being made out of decent quality steel...with luck medium carbon steel which will bump the strenght way up compared to mild steel.

But I have also seen some pretty cheap nasty U bolts that show definite deep sharp impressions where they are bent, with rolled threads that are not clean and would probaly be less than 50% thread depth and who knows what sort of steel they are made off

If you went to a trailer manufacturer that could be bothered building a better quality winch post, they were probably inclined to pay the extra $2 for decent "U" bolts.

Hell lots of the manufacturers can't even be bothered fitting washers.

cheers

[cormorant]

Hi Feral

Yeah i don't think people understand the forces involved until they see it.

Last year we had a 20k/h hit up the boot on our falcon when stationary at the lights ( no trailer attached) when the bloke behind was not concentrating. Didn't feel like too much and not enough to set his airbags off and he was in a lighter vehicle .Honestly if the repairer had popped in 10 broken plastic clips , buffed out a small scratch jo bloe on the street would have been none the wiser. Insurers / repairers did the right thing and replaced our towbar and every rear bracket , all bolts ( which at the time I thought was a bit of a con milking the insurance ) but when I saw the old tow on the ground next to the new one and saw it not sitting flat on the concrete, , marks on threads of bolts I realised they were doing the right thing. New cars plastic on both cars and small brachets had deformed and dissapated so much of the impact. The repaire Oxyed the old towbar so it could not be scavanged and old ball went out as well. Nice when the system works

Wish I could find some old footage of a boat trailer in those accident tests in extra slow mo and there was some truck ones with loads as well. It was a USA one and it showed just how much a boat moved when the vehicle hit a solid object and the true force of momentum. . Talk about steel flexing and straps stretching - I'm talking daylight between boat and trailer, motor tilt trim overpressuring and nearly snapping off ( well it would have been well stuffed) and like you the rear of a 80's wagon rippled so the back doors would never open and a banana. Huge difference when they do those tests and it is a solid stop-- ouch

After a event like that where the insurers know the speed and momentum it seems incomprehensible nearly criminal that the insurer didn't write off the trailer as no engineer in his right mind would approve it for ongoung use after that sort of event. Another smaller accident that normally wouldn't be a issue may be a disaster with hitch bolts , the hitch itself and any other weld or bolt possibly already past it's design loads. Thankfully there is a written off register no but a hell of a lot more cars and trailers should be on that list.

Truck ones were horrific showing the difference between the same load chained down and one with a few inches of slack. The few inches of slack created enough momentum to snap chains and crush the cabin

There was photos on here years ago of a trailer that with a plate alloy on it that rolled or broke a hitch and chains and it showed the winch post gone, , chassis bent,straps still attached to trailer but boat was 30 feet away 2 foot deep into the ground and another where it showed stretched chains and fractured welds.

Been a fair few photos on here of stuffed winch posts from fatigue, age, bad design and small accidents as well.


Edit - here is a 800kg braked box trailer behind a escort at only 50km/h:o I think the trailer comes off the ball ( but maybe not) and I can't see a safety chain- fuel tank would be cactus. It has pushed all teh way to the back seat through the spare tyre?

http://www.youtube.com/watch?v=5A9fXXDHfl0&NR=1

[robothefisho]

Sorry but I think that is a load of rubbish...and that is the line lots of truckies who don't like the current performance standards are pushing too..... but there are plenty of those guys getting fined every day



cheers

Oldboot,

Apologies if this seems short but I lost my full reply and can’t be bothered re typing it atm.
No need to say sorry for disagreeing with me, I take no offence and don’t think there is any reason to.

To secure a boat legally would require a minimum of 4 certified fixing points on the trailer, that means qualified welders certified to do it, welding on proper fixing points, probably welded to thick base plates. Then the boat would require engineered fixing points, on a plate ally boat not too much drama, on a pressed tinny, good luck. On glass probably still more trouble than it’s worth. On top of that, you would require rated chains and ratchets. Then an engineer’s certificate to prove it’s legal. If you had change out of 5 grand I’d be surprised.

As for truckies, it is impossible for them, because they are carrying equipment/goods that are temporary loads. To bring a truck carrying 2 pieces of large equipment to standard cost approx 20 grand. That was for machinery that only ever moved on that truck.
No trailer manufacture or private person will ever go to those lengths so a boat can be towed around 100% legally. It simply costs too much.
As has been mentioned by you and others, a good chain and turnbuckle at the front and ratchet straps both sides at the transom is about as good as it will ever get.

[PinHead]

why do some want to try and complicate everything and try and espouse their so called small minded knowledge. I recon some blokes would want a NATSPEC and NATA certification on the elastic on their undies before they put them on every morning. Give it a break..life is meant to be enjoyed..not worry about legislation for everything you do..strap the bloody boat down and get out and enjoy yourselves.

[robothefisho]

Works slow and colouring in books are frowned upon..

[oldboot]

Oldboot,

Apologies if this seems short but I lost my full reply and can’t be bothered re typing it atm.
No need to say sorry for disagreeing with me, I take no offence and don’t think there is any reason to.

To secure a boat legally would require a minimum of 4 certified fixing points on the trailer, that means qualified welders certified to do it, welding on proper fixing points, probably welded to thick base plates. Then the boat would require engineered fixing points, on a plate ally boat not too much drama, on a pressed tinny, good luck. On glass probably still more trouble than it’s worth. On top of that, you would require rated chains and ratchets. Then an engineer’s certificate to prove it’s legal. If you had change out of 5 grand I’d be surprised.

As for truckies, it is impossible for them, because they are carrying equipment/goods that are temporary loads. To bring a truck carrying 2 pieces of large equipment to standard cost approx 20 grand. That was for machinery that only ever moved on that truck.
No trailer manufacture or private person will ever go to those lengths so a boat can be towed around 100% legally. It simply costs too much.
As has been mentioned by you and others, a good chain and turnbuckle at the front and ratchet straps both sides at the transom is about as good as it will ever get.

There is no requirtement in the guidelines for there to be certified or rated attachments on any loads... nor are there any specific requiremant for the attachment points on the carrying vehicle to be formally rated or certified.....there is an implied duty of care that the attachment points and the result are adequate, but no specific engeneering certification requirement, like there are in lifting......it is nowhere near as rigid as the overhead lifting or height safety regs

The guidelines do very much concentrate on the practical, particularly in the sections aimed at drivers........before you start throwing the baby out with the bath water and saying it is all to hard, please go an read the guidelines at least the chapters aimed at drivers.

As far as the requirements for rated items it mainly concentrates on lashing and tiedown materials like straps, ropes and chains..and as i said before most of the straps you see for sale these days have at least some sort of load rating on them, chain and chain related gear suitable for load restraint is all ready pretty well controlled.

Rope well ..there are very good reasons it is very much falling out of favour for load restraint.

In fact I would say that it realy would not be that difficult to 100% legally restrain a boat on a trailer...it realy only takes a little learning about the requirements and methods and a little thaught..it realy isn't all that hard.

In fact...on a lot of rigs, it could simply be a case of securing the bow of the boat indepedently of the winch post..... in addition to the usual over the top strap.

Which is what most informed owners are doing now any way.

No major hairy deal... just a bit more thaught than "she'll be right mate"

And the cost.....maybe $100.....some chain, a few shackles, a turnbuckle and maybe a new strap or two.

cheers

[Feral]

Yeh but when you say standard "U" bolts.....ya mean decent quality ones or cheap chinese crackers.



If you went to a trailer manufacturer that could be bothered building a better quality winch post, they were probably inclined to pay the extra $2 for decent "U" bolts.

Hell lots of the manufacturers can't even be bothered fitting washers.

cheers


Not sure where the U bolts were made, came from the local trailer parts joint.

Certainly went to a good local trailer manufacturer - Me!. Would not touch the light weight crap they pass off for trailer frames these days with a barge pole.

7084970850

[ozscott]

Cormorant nice vid. That bar of course is that crazy extra light duty curving bar (rolled pipe might do a better job ;) ). The hd Australian Reese don't dont do anything that tragic from what i have seen nor should they given their build. Having said that an acc with 2 tOnn or so on the back is never pleasant. Cheers

[tunaticer]

I build some rather large silos in my line of work that are transported to various locations right across this country.
One thing I have noticed with truckies is they always know better and stick to their way of tying things down regardless of better advice offered.
The common concensus for large tanks is to run crossing chains diagonally fro0m the trailer to the opposite side top attachment area on the tank.
This is not good practice because if one chain fails the other chain will pull the tank sideways on the truck and you will lose the load guaranteed.
The only way to properly secure these large items is one short chain in each corner, keeping the chain as short as possible and close to vertical as possible to the tie down points.
If one chain fails the other three are still at their shortest possible length and can not come loose.
The number of times I have argued the point with truckies is rediculous and even if i make them tie down as i request, they often pull up just up the road to tie down how they think it should be. Of those few dozen trucks that have tied down their way, about 30% of the silos have suffered movement or damages from movement or completely come off the trucks from being chained diagonally. Not one load that has had 4 short chains has ever moved or suffered damages.

The same principles apply to boats on trailers. Keep your bindings short and direct to the tie down points and you will suffer much less if you suffer a breakage of something.

Sometimes less is more.

[oldboot]

I can see that.

Apart from making one chain dependent on the other for its effectivness, cross chaining also puts the tie down at a mechaincal disadvantage.

cheers

[PinHead]

I can see that.

Apart from making one chain dependent on the other for its effectivness, cross chaining also puts the tie down at a mechaincal disadvantage.

cheers

want to expand on that..give some point loadings..sheers factors etc.
We are talking about a boat on a trailer not a bloody silo..I bet the silo is on a flat bed..totally different to a boat sitting on a trailer.

[oldboot]

The point is that there are a lot of "tried and true" methods of securing loads that simply prove to be ineffictive and possibly dangerous.

And lots of people simply wont be told.

cheers

[PinHead]

so you cannot give point loading and sheer factors for a boat on a trailer and the chains holding it ?

as I said..winch strap and safe chain..strap over the rear works a treat...there really is no need for anything else.

[fairpractice]

Hi. have had a winch post tear its weld, winch hook straighten, winch strap bust.
Now use chain and turnbuckles at front AND a length of telecom type rope wrapped from bow to trailer frame about 10 turns. great shock absorber and insurance on thousand km. road trips.
The degree of tie down depends on the distance i travel, with the obvious safety factor for traffic accidents.
cheers john

[nautimax]

Ok some further information about this whole bolt strength thing.


Now who knows what steel the "U"bolts are made off AND consider the threads are mostly rolled not cut and thus are not full depth and not all that strong...so the 300KG aint all that unrealistic, particularly if you calculate from "proof load" (the strength before the bolt starts to stretch).

cheers

...rolled threads don't need full depth (to retain strength) as opposed to cut threads. The advantage of rolled threads over cut threads is they are less susceptible to fractures because the metal (grain) is made to flow and shaped into the threads...as opposed to cutting across the natural grain of metal when dies are used to cut threads...anyways, most commercially available threaded fasteners have only 75% thread depth unless you spec otherwise it will cost a bit more....