Trailers - 1 axle or 2? Bunks ior Rollers?

[mark_turner]

I am asked for advice on a trailer for an approx 1.2tonne (inc engine and kit) 20foot displacement hull riverboat for use on the Thames.

Which would be recommended 1 axle or two?

Are twin axles harder to manouvre? (we will need to spin it 90 degrees on its axis by hand on a tarmac drive to 'park it' in the drive. )

Is height of tow ball a problem with a twin axle? (in order to ensure the correct distribution of load between the two axles). We wouldn't want to have an ugly great plate to adjust the height of the tow ball to suit the trailer.

As the boat is going to be used in fresh water only, is maintenance of a twin axle going to be a problem? (I can see that it might be if the trailer were to be regularly dunked in salt water).

Any other advantages and disadvantages?

ALSO

Is it worth paying the extra for full rollers rather than just keel rollers and bunks? Will it make a real difference to getting the boat in and out of the water? (given that dunking in fresh water is likely to be less harmful than dunking in salt).

Your views would be very welcome.

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[snowleopard]

with that weight, 2 axles are essential.

turning by hand will be a pain but possible. a rope to the car or other strong point will help.

the towball height isn't particularly critical, the important factor is the load on the towbar: get the car manufacturer's recommendation then adjust the position of the boat on the trailer to suit (you can use a bathroom scale under the jockey wheel to measure it). once you have done this, make some marks so you can always load in the same position.

can't speak for full rollers as i've always used a crane but remember there will be no friction to stop the boat sliding so you'll need fore-and-aft lashings as well as tie-down straps.

if you choose to run the trailer into the water, remember that at the end of a journey the wheel bearings will be hot. when you run the wheels in the water the rapid cooling will suck water into the bearings. keep them well packed with grease & allow cooling time before launching (that's what waterside pubs are for).

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[chriscallender]

Not so sure it can't be done on one axle - its possible to get axles and tyres that can take up to 1800kg so I believe it is perfectly possible to have a single axle trailer that can carry 1.2 tonnes.

That said, I've towed heavy loads (not boats) with both one and two axles and I much perfer the extra stability of two axle trailers, and extra stopping power of two sets of brake pads. Downsides are 2x as much maintenance and a pain to spin it around in its own length depending on how much muscle power you have available.

So I'd say the decision might well come down to how you plan to use the trailer. For regular 100 mile trips especially on A roads and motorways then 2 axle would definitely be a benefit, but if its just for the occasional five mile trip then the extra maintenance (wheel bearings brakes) probably don't make sense - just make sure the setup is legal and take it a bit more slowly. Even in fresh water the bearings and brakes are going to have to be maintained, although its clearly much easier since you don't have to worry about flushing out the salt water, and bearings are likely to last much, much longer.

Chris

<hr width=100% size=1><P ID="edit"><FONT SIZE=-1>Edited by chriscallender on 11/03/2003 12:04 (server time).</FONT></P>

 

[jleaworthy]

Good advice from Snow Leopard. I would just add:
1. Your main problem of immersion even in fresh water will be with the brakes rather than the bearings. You cannot have an unbraked trailer loaded above three quarters of a ton. Suggest you make sure the drums are well dried out each time and that the bits that can be lubricated are well greased.
2. Fit a winch to the front of the trailer together with a snubbing post.. This will make recovery much easier provided , of course, you have a strong point on the bow of the boat.
3. If you fit full rollers you will be able to recover the boat with less immersion of the trailer either by winching it onto the trailer or by driving it up using the boat engine provided the trailer is well anchored on car or tractor hitch. It also makes single handed recovery possible. And before anyone criticises - it works!

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[tr7v8]

At this size I'd always go for 2 axles rather than one, it reduces the brown undies issue when you have a tyre go for a start. As regards spinning it around I see people really struggle with this, normal way is wind jockey wheel full up lifting front axle off ground and manouver. On an empty trailer this is easy, on a full one I'd debate getting one of those motorised helper motors that go on the tow hitch.
As regards towbar height it is important that both axles are loaded equally, which can mean fiddling with the ball height. Another reason for getting the height right is that if you don't the trailer when loaded tends tohobby horse or porpoise all the time which is very unsettling to the occupnts of the tow vehicle!

Jim
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[neale]

A twin axle trailer with boat on weighing over 1.5 tons will not be easy to spin on its axis. I have great trouble spinning my empty 3ton trailer on its axis and this weighs around 600kg. In the summer with soft tarmac you risk damaging the surface of your drive. Having said that I am not sure you will get a single axle trailer to take the weight you need.

Rollers will make your life easier although in my opinion, bunk trailers offer better support to the hull. If you were launching and recovering only very occasionally I would go for bunks, if you are going to do it every weekend then get the rollers.

Neale

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[c_roff]

Yes, if you're towing a 4 wheel trailer the ball hitch height IS critical. If the ball on the towing vehicle is too high there will be too much weight on it and the trailer will tend to ride on the rear wheels more than the front ones. It will also be difficult to hitch up, even with a decent jockey wheel.

If the ball hitch is too low then the trailer will have a tendancy to pull the back of the towing vehicle up, the trailer will tend to ride on the front wheels and it will be prone to snaking.

4 wheel trailers are more stable but a correctly balanced, slightly nose heavy 2 wheel trailer usually gives a more pleasant ride. As the road surface undulates and the trailer rocks in the fore and aft plane 4 wheel trailers can have a tendancy to snatch the back of the towing vehicle up and down more than a two wheel equivalent.

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[Sandro]

An interesting article on PBO of some monthes (or years?) ago reported only pros for the two and cons for the four wheels. And the swinging by hand was not taken in account.
Actually the load is quite a lot for a single axle. You should ask some builder.
Good luck


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[poggy]

Hi,

What sort of vehicle will you be using. The combined weight of boat, engine and trailer could be substantial. I would look at your load capacity and then look at the trailers and total weight and nose weight.

I used to drive my RIB onto the trailer with full rollers but I had some good strap points to stop the boat moving back once it was on.

Poggy
Poggy

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[Avocet]

Just a few thoughts which might help:

1. It's perfectly possible to get trailer suspension units and tyres that can handle 2 tonnes on one axle so if you want one axle that's not a problem. Look at the Indespension or Towsure websites. This will make the trailer much cheaper to build and easier to spin on the drive. The main downside is that the wheels and tyres will be quite big. This will mean the boat sits higher up and you have to put the trailer deeper into the water to float the boat off. To my mind, that's where the single biggest advantage of a twin axle setup lies.

2. I think the towball height is critical on a twin axle trailer for the reasons stated i the other posts. I have one and the ride is pretty horrid because it pulls the back of the car up and down as it pitches over bumps. My axles are quite far apart. In retrospect, I think this was a bad idea because it accentuates the "porpoising".

3. If your car is post 1998 (maybe 1996) it needs a type approved towbar. This will have the maximum permissible nose weight stamped on it.

4. It's possible (I think) still to buy "bearing savers" for boat trailers. These are spring loaded hub caps that maintain a positive pressure inside the bearing even when dunked into cold water so that the air inside the hub contracts. This should stop them sucking water in.

5. It might be worth talking to a specialist boat trailer manufacturer - it is sometimes surprising how cheaply they can do a professional job.

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[Strathglass]

If you can get a trailer made to match the boat then go for a double axle. It will be very difficult to spin by hand.

I managed to fracture two of the (well rusted) suspension units when trying tight reversing on a four wheel trailer with a one ton load (E boat)

A single axle trailer is easier to home build and to get the nose weight and the drawbar height correct for the towing vehicle. It will also be much easier to manhandle into a tough parking space. It would also be less expensive.
But, it will not be as stable when towing as a good four wheel trailer.

Iain

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[grinch]

I prefer the peace of mind you get with a twin axle trailer although they are more difficult to manoeuvre. My trailer has to be reversed into its parking spot by hand so I just remove the two back wheels. It then spins on its axis. Towball height is critical with a twin or it will not ride correctly. This is easily remedied with an adjustable towball plate available from any good trailer shop. I also prefer rollers to bunks as the boat comes off a lot easier although don't rely on the winch strap as the only restraint. I use a short length of chain attached securely to the trailer with a snaplink to the boweye as back up. Two heavy duty ratchet straps through eyebolts on the transom hold the back down. If maintained regularly, wheel bearings are easily removed and cleaned in a matter of minutes although it is wise to always carry a spare set.

Grinch

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[gjgm]

as mentioned, you need to check your car tow capacity, (these trailers are not light ) and check the width of the boat. I ve been launching 18-24ft boats, and always with full rollers. There s no doubt that makes it alot easier. If its an occassional launch,maybe you can manage with bunks, but you dont want getting the boat off and on the trailer to ruin your day each time. Incidentally, if its a shallow launch, although you can use ropes, and you are having a trailer made, I had a hinged 2.5m extension with a hithch fitted for getting the trailer adequately into water at some locations. Try sbs trailers in Midlands. Regards spinning it 90 degrees, 2 axles will be harder. And an ugly tow bar plate is far preferable to the car and boat upside down at the roadside, one axle or two. Its going to be at least 1.5 tonnes right behind you, so set up is critical to your safety. (Incidentally sbs use alko axles-bearings, which are maintenance free, and allowing for cooling after travel, you shouldnt have an issue with launching) Happy boating ....

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[AJW]

Whilst I agree that SBS trailers are excellent and that the company is very helpful I have to disagree about Alko bearings. I have them on my dirty great SBS trailer and the do eventually dry out, rust and fall apart (if not checked regularly) after a season or twos dunkings in sea water.

Sounds like you need a twin axle trailer. Would recommend a "motor mover", battery powered wheelie device that enables you to move the thing around under its own power to help you park it. Heaving that much trailer and boat around with man power, particularly with twin axles is gonna give you a slipped disc or a hernia!!

AJ

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