trailer build

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Sailfishing

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Does anyone know of any where I can get trailer plans or guidance on designing one?

The build is not too much of a problem its just the design and costing, is it much cheaper to build your own? Cost of galvanising?

I'm looking at a roller coaster design for an 18ft trailer sailer (Sailfish 18)

Any help gratefully received,

Kev
 
There are some basic plans in the Indespension catalogue (I have a 2002 edition). The basic boat trailer does not show any rollers though.

I think as the fashion to home build has declined Indespension have not bothered to update the plans.

Last time I had galvanising done (4 years ago) it was £1 per Kg so a small trailer would be about £100.

Peak Trailers are a good source of trailer parts and custom build axles to your required width (and then galvanise).

http://www.peaktrailers.com/
 
Indespension Roller Coaster and Super Roller Coaster designs will be suitable. The biggest will take a 24ft LOA boat. As for building your own there have been some legal obstacles put in the way of economical self build, as you can no longer use second hand vehicle brakes, as you used to. One way to build a boat trailer if the boat is not too heavy is to use a chassis from a scrapped caravan as the basis. Galvanised caravan chassis tend to outlive the bodywork.
 
Kev
Over the years I've built a number of road trailers for boats and I have to say that with all the agro (regs) that goes with building a trailer now it's hardly worth it!!

All of my "builds" included using "Mini" brake parts/drums etc, and I've built both single axle as well as double axles trailers. I've always used Indespension parts and when I've added up my time etc etc it's really not worth it ~ go and buy a purpose built trailer ~ road legal and CE marked!!!!

Peter.
 
It is a sad reflection on the "Nanny" state that we are forced towards commercial products when home brew can be very satisfactory. Fortunately it is not so bad here though a trailer still has to be inspected for licensing. And be registered and insured every year.

My trailer has essentially a square frame going back about 3/4 of the length of the boat with sides tapering in to about 1 metre from the coupling. A square section draw bar goes from the coupling back about 3 metres to go through the side rails tapering in then back through one cross member and meeting another. The frame is about 1.8 metres wide to allow clearance for the wheels all remaining within max legal width. 2.5m here

It has standard leaf springs but the axle has a drop design so that wheel centres are about 15 cms above the centre of the axle. This is because you need the axle to be under the chassis by a suitable clearance. But if you use large road wheels a straight axle would make the chassis too high. The drop is achieved by welding plates on the end of the axle with stub axles from front of rear wheel drive car is bolted on. In this case the whole drum brake system can be attached behind the stub axle.

The rollers are simply attached to a ladder of two angle iron rails up the centre and at suitable pints by risers of angle iron at the sides. You should try to get most of the weight taken by the centre rollers as this is a strong point along the keel.

In replacing the draw bar I fitted that at an angle downwards at the front so the boat actually sits at a stern down angle. This puts the back of the trailer lower making the winching on and rolling off easier. You should check this boat angle when attached to your car before finalising the attachment of the draw bar. With this arrangement I can actually winch the boat onto the trailer from dry sand.
Make the winch post (or axle assembly) adjustable fore and aft so you can set the load balance correctly. 10 to 15% total weight on the hitch.

Lights are best mounted on a board so completely removable. I attach them to the stern rail of the boat or the back of the trailer if towing empty.

Avoid using box section metal as this rusts from the inside quickly. Mine was originally made from light weight but large dimension U channel with a small return on each edge. The advantage is that you can see paint or galvanise all sides of the metal. Box section should be galvanised and or have a lot of old oil run inside.

You should allow that you may want to leave the boat on a mooring. In which case you will want to antifoul the bottom while on the trailer. That is what I do but with difficulty. I need to jack the trailer and tilt it so I can get under then slide the boat back to enable painting where the rollers are.

You need to consider the possibility of dropping the cb (keel) when on the trialer. Make sure that cross members are clear in this area and perhaps have removable rollers.

All this is predicated on a flat bottomed boat. ie no fixed keel. You will need a redesign to allow for a stub keel or bulb on the c/b.

Just a few thought I hope it helps olewill
 
Towsure

I've built a number of trailers over the years and have found Indespension excellent for information. They also sell parts but rather expensive IMHO.

I have found Towsure to be very reasonable with prompt delivery.
 
That was my un-asked question. If you build a (braked) trailer how do you go about getting the trailer plate correct and legal.
Or do people just not bother and risk prosecution?

I understand the police have occasional "hits" on places like motor-racing circuits on club race days and check over everyone leaving with trailers.
 
I am currently building a trailer for a 25 ft 2000kg fin keel yacht, I have done some research for finding best value parts and have also done a lot of research to make sure it is road legal.
Basically the trailer's load capacity is based on the axle and coupling capacity. You need to take into account the actual weight of the trailer and you are left with the maximum capacity.
To make sure the trailer is legal, it must be no longer than 7.5m and no wider than 2.9m (also the load must not project more than 310mm each side of the trailer, it can project over 2m from the back of the trailer but you need a hazard marker to show this.
Maximum towing total towing weight (for a car or 4x4) is 3500kg.
And one last, but quite important thing is the trailer must have a VIN plate, showing the makers name (ie yours) the date of manufacture, the capacity of each axle and the maximum load capacity. These are actually quite easy to do, you can buy blank VIN plates for the job on ebay and stamp the details on from a stamp set you can get from machine mart.
Have a look at the NTTA's website for more details regarding trailers.
 
Interesting. I know the regulations and have used the hitch limit and suspension ratings as a guide before but I wonder if the construction of the trailer itself has any bearing on the weight limit for the trailer.
If you're not a stress engineer, how can you be certain that you have built the trailer to a sufficient standard?
 
We're about to get saddled with more legislation - the "Individual Vehicle Approval" inspection regime will include trailers from (I think) 2012. I've built a few trailers before now and I do (VERY) basic hand calculations. I also tend to use a pretty generous factor of safety. To be honest, a steel trailer rarely sufferes a catastrophic structural failure. They generally start to bend or twist if they're not up to the job. Obviously, I'm not exactly advocating the complete "suck-it-and-see" approach, but an element of that is, in my view, acceptable. Obviously you inspect it carefully and frequently after the first few trips round the boat club yard and then after the first few miles on public roads, and so on.

I much prefer these people:

http://www.trailerpartswarehouse.co.uk/

To Towsure. I find their stuff to be better quality on the whole. That said, it's still quite expensive to put together your own galvanised, braked trailer these days. It's well worth looking round for something that needs a bit of tidying up.
 
Hi Avocet. My experience with a trailer now nearly 30 years old is that the trailer is a consumable. Rust and corrosion are a constant problem.
You might get a good s/h trailer but more likely get one with a lot of hidden rust. Most trailers not only dunked in salt water but then stored outdoors.

As for trailer integity (strength) almost any trailer is strong enough to begin with but will be progressively weakened with corrosion. olewill
 
Agreed - I guess what I should have said is that the second hand trailer ought to be regarded as little more than a donor for a towing hitch, suspension brakes, rollers etc but the structure is, as you say, a 'service item'! That said, hot dip galvanising and careful use of open sections that don't hold water can give them quite a reasonable life.

Over here, small trailers don't need to be registered so the authorities have no way of knowing who's got what and how old it is. On top of that, there is no obligatory periodic roadworthiness inspection and (currently) no initial design inspection. We do have our "Construction and Use" laws and they certainly do contain requirements for trailers but they aren't very well enforced! (Not in my opinion, at any rate)!

I have a big 4 wheel trailer that I use for carting junk about. I bought it second-hand and I genuinely have no idea how old it is. It doesn't have the current auto-reverse brakes that a new one would require or any kind of plate showing its carrying capacity (which, I therefore assume to be 4x the load rating on the tyres)! I've replaced the old spring over-run hitch with a damped one since I've had it and I guess the frame will need serious structural work in the next few years, but as it (probably!) predates a lot of the current legal requirements, I can't see why I wouldn't be able to replace every single part of it and still not have to meet current requirements - it's a bit like "William the Conqueror's knife" (six new handles, three new blades, a couple of new lashings and still as good as new)!
 
Finding the information is pretty tricky.
One aspect I found is [ QUOTE ]
1982 regulations demand that all trailers, including unbraked ones, must be clearly marked with their maximum gross weight in kg. This may be checked at any time by the police at a weighbridge. Since 1st January 1997, all unbraked trailer plates must show the year of manufacture.

[/ QUOTE ]
but when I sold a dinghy on a trailer to a Police Vehicle Examiner, he seemed very unconcerned about trailer age or plating (or even having a proper rear number plate) /forums/images/graemlins/shocked.gif
 
Yes, but of course, my trailer was built before 1982...

...I'm sure quite a lot were! That's the whole point, if there's no compulsory system of registration / identification, the authorities will have no idea how old a trailer is.
 
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