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Old 05 January 2009, 07:48   #1
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Trailer build

I am refurbishing a 6.5m Libra Rib with 2x Yam 75's. It is apart at the moment and tubes are with Paul Tilley for replacement. The boat is in Muscat and has been stored and launched by tractor from a basic trailer which is now u/s.
I want to make a road trailer to take the boat to launch sites for diving.
i have the trailer pictured below but side rails are rotted out. I plan to cut the independant axles off and the triangular 'front end' and then add 2 new rails with cross beams, keel rollers and bunks. i would be grateful for advice on:

First size of box to use for main rails. i am thinking 120 x 50mm - any advice?

Secondly size of box for cross members (say 4)

Finally positioning of twin axle. I have access to measure the axle layout of the same size of rib on a professionally built single axle trailer. I can measure the position of the single axle in relation to say the stern of the rib and mark that point on my on my new trailer. However where should I position the twin axles in relation to the single axle mark. Axles centred equidistant around it, rear axle centred on mark etc...

many thanks in advance
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Old 05 January 2009, 11:02   #2
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Originally Posted by Andy Young2 View Post
I am refurbishing a 6.5m Libra Rib with 2x Yam 75's. It is apart at the moment and tubes are with Paul Tilley for replacement. The boat is in Muscat and has been stored and launched by tractor from a basic trailer which is now u/s.
I want to make a road trailer to take the boat to launch sites for diving.
i have the trailer pictured below but side rails are rotted out. I plan to cut the independant axles off and the triangular 'front end' and then add 2 new rails with cross beams, keel rollers and bunks. i would be grateful for advice on:

First size of box to use for main rails. i am thinking 120 x 50mm - any advice?

Secondly size of box for cross members (say 4)

Finally positioning of twin axle. I have access to measure the axle layout of the same size of rib on a professionally built single axle trailer. I can measure the position of the single axle in relation to say the stern of the rib and mark that point on my on my new trailer. However where should I position the twin axles in relation to the single axle mark. Axles centred equidistant around it, rear axle centred on mark etc...

many thanks in advance
Any idea on what your boat will weigh ?

I'd go 120mm x 50mm x 6mm for your rails and then run a smaller rail (30mm x 30mm x 4mm) above it with some 120 mm off cuts as spacers to make two ladder sections.

I would run the two 30mm box sections onto the existing front triangle to give you an overlap of joints and also weld brace sections under the 120mm x 50mm box to give you a stronger join.

I think it's best to bolt the cross members to the rails with U bolts so you can move them and use them to mount the keels rollers. I'd do the same with the axles so you can move them forward and backward along the rails to suit your boat's loading. I bolted my axles to two long cross members with short rails at either end so you can then use these as fixing points for the bunks mud guards etc and it spreads the load.

If you want any pictures give me a shout

Jim
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Old 05 January 2009, 14:07   #3
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Jim I'd be interested in seeing the pictures please.
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Old 05 January 2009, 23:54   #4
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Jim
thank you for your reply and for giving me some excellent ideas. I would like to see pictures. The problem I have in Muscat is obtaining things like U-Bolts and chandlery items. I shall get on the case today and see what I can source from Dubai.
The boat is a Libra 6500R dry weight 745kg, 150L fuel tank, 2 x 75hp Yamaha O/B.
Pictures below show the boat on the tractor launch trailer, resting on webbing straps.
Third picture shows how the independant axle is connected to the trailer rail via a bracket.
Final picture is looking forward to the forward 'triangular section' that contains tow ring, jacking leg etc (this is all sound)
From your suggestions my thought is to weld the two axles together using a short rail of 120 x 50 across the brackets to make a bogey. The main rails can then be inset 50mm each side on the forward triangular section so that the bogey can slide up and down to get the perfect nose weight on the trailer once the boat is completed and loaded.
Once positioned the bogey can be U-Bolted in place. Bunk brackets etc can also be U-Bolted in place. The advantage of this method is that I don't have to worry about positioning and welding the axles on at this stage.
It will be hard for me to get this galvanized. I propose to seal all the box section with welded patches is this the way to go or leave them open and flush out.
I look forward to seeing your pictures and further advice.
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Old 06 January 2009, 01:48   #5
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Jim
Another thought; the bottom of the main rails will sit above the axle by say 50mm as the rails will be on top of the axle brackets. If I mount the rail crossmembers which will bear the keel rollers flush with the top of the main rails the rib will sit pretty high, meaning i will have to get my car further down the launching ramp than I would like to launch/recover.

Therefore I would like to rib to sit as low as reasonably possible on the trailer. To this end the crossmembers will either need bending or welding into a flattened v-shape so that the keel clears the axle by say 75mm. Do you think this is enough clearance for the type of axle? I am unable to testhow much the suspension deflects until I get it all together however the sheet steel that makes up the current trailer bed is 5-6mm.

What size of box section would you recommend for the crossmembers bearing in mind the weight of 745kg plus, fuel and motors - I am thinking of using 4 crossmembers and 4 keel rollers plus a bow roller/stop.

Once I know what size of box section I can then see if I can find anyone to bend the steel as I need it. Attached are two examples from trailer under another rib undergoing refurb. These crossmembers look like 120 x 50 but less than 6mm. They 'drop' by about 150-175mm from the level of top of the chassis rail. The third picture appears to show abou 150mm clearance above the Land Rover tyre but this trailer has no suspension.

Thanks again for your advice
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Old 06 January 2009, 04:16   #6
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Quote:
Originally Posted by Andy Young2 View Post
Jim
Another thought; the bottom of the main rails will sit above the axle by say 50mm as the rails will be on top of the axle brackets. If I mount the rail crossmembers which will bear the keel rollers flush with the top of the main rails the rib will sit pretty high, meaning i will have to get my car further down the launching ramp than I would like to launch/recover.

Therefore I would like to rib to sit as low as reasonably possible on the trailer. To this end the crossmembers will either need bending or welding into a flattened v-shape so that the keel clears the axle by say 75mm. Do you think this is enough clearance for the type of axle? I am unable to testhow much the suspension deflects until I get it all together however the sheet steel that makes up the current trailer bed is 5-6mm.

What size of box section would you recommend for the crossmembers bearing in mind the weight of 745kg plus, fuel and motors - I am thinking of using 4 crossmembers and 4 keel rollers plus a bow roller/stop.

Once I know what size of box section I can then see if I can find anyone to bend the steel as I need it. Attached are two examples from trailer under another rib undergoing refurb. These crossmembers look like 120 x 50 but less than 6mm. They 'drop' by about 150-175mm from the level of top of the chassis rail. The third picture appears to show abou 150mm clearance above the Land Rover tyre but this trailer has no suspension.

Thanks again for your advice
Hi

I've not got my camera at work today but will post pictures tomorrow

Jim
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Old 06 January 2009, 04:32   #7
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Many thanks Jim
I have sent my enquiries out regarding steel and U-Bolt availability and will get the old trailer cut up into the components. I have been amazed at the ingenuity of the local suppliers. I had missing ignition keys for Johnsom motors and a chap had keys cut to fit the barrels within half an hour.
regards
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Old 07 January 2009, 04:49   #8
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Some pics of the trailer during build, showing the cross members etc

Mine has a cradle for the boat but you can see the ladder rails and the cross members with the longer ones at the axles held on with u bolts. If you canít get u bolts you could weld some flat bar onto the cross members and bolt over the top of the rails, you can also see the stiffening bar over the join in the rail.
Third pic is of the longer cross members for the axles etc
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Old 07 January 2009, 08:07   #9
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couple more
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Old 07 January 2009, 08:38   #10
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Off topic, but who did you use for galvanising?
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Old 07 January 2009, 08:54   #11
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Off topic, but who did you use for galvanising?
There's a firm a mile down the road from me "Premier Galvanising" not the best but not bad
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Old 12 January 2009, 03:35   #12
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Thank you very much for posting the pictures of your trailer which have given me some good ideas and something to aspire to.
I have been trying to source steel (120 x 60 x 6mm) however the closest I can get is 100 x 50 x 4mm. Is there any way I can use this section with a ladder type construction?

If not what size of U-Section channel should I be looking for?
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Old 12 January 2009, 12:21   #13
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Originally Posted by Andy Young2 View Post
Thank you very much for posting the pictures of your trailer which have given me some good ideas and something to aspire to.
I have been trying to source steel (120 x 60 x 6mm) however the closest I can get is 100 x 50 x 4mm. Is there any way I can use this section with a ladder type construction?

If not what size of U-Section channel should I be looking for?
Yes I'd use 100 x 50 x 4 for the bottom section and for the spacers (rungs) and either 50 x 50 x 4 for the top or the 100 x 50 x 4 again

Jim
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Old 11 February 2009, 02:35   #14
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Here is progress so far
this trailer will be for 6.5m rib with 2x75 Yamaha and 150L internal fuel tank.
I plan 4 or 5 crossmembers with keel rollers, i pair of rollers at rear crossmember to guide hull to centre then to fit bunks.
My plan is to make trailer and load bost on fully laden, then trim the trailer to get nose weight right. I have put axles on a separate frame so I can slide them up and down to get balance right then clamp them with 6 U-Bolts.
I am going to make cross members from 80x30 box
Any comments that would help me see potential pitfalls in this design would be much appreciated
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Old 11 February 2009, 03:09   #15
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Here is progress so far
this trailer will be for 6.5m rib with 2x75 Yamaha and 150L internal fuel tank.
I plan 4 or 5 crossmembers with keel rollers, i pair of rollers at rear crossmember to guide hull to centre then to fit bunks.
My plan is to make trailer and load bost on fully laden, then trim the trailer to get nose weight right. I have put axles on a separate frame so I can slide them up and down to get balance right then clamp them with 6 U-Bolts.
I am going to make cross members from 80x30 box
Any comments that would help me see potential pitfalls in this design would be much appreciated
Looks good so far to me, she's a great welder

I'd make the rear cross member heavy duty twin box and u bolt it on so you can move it on the frame to suit your rib

Jim
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Old 11 February 2009, 03:33   #16
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Andy,
Looking good so far .....looks a bit wide though but pics are deceptive, just means extra caution when driving .......i also noted you have welded up the ends etc .........every piece of box section you have must have a hole in it (i used 12mm) or the trailer wont be accepted by the galvanisers.....normally the ends are left open ......I think its so the box section sinks in the hot dip bath ....even the small pieces of section between the lower and upper chassis members need to be drilled ....top and bottom

I assume you are putting on boat rollers with swinging beams ...i'll try and dig out where i bought my rollers from

galvanisers in scotland run at £430 per ton ......both trailers i made around similar size to yours were around £120 -£150 inc vat

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Old 11 February 2009, 04:19   #17
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I assume you are putting on boat rollers with swinging beams ...i'll try and dig out where i bought my rollers from

Ian



Quote:
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I plan 4 or 5 crossmembers with keel rollers, i pair of rollers at rear crossmember to guide hull to centre then to fit bunks.
Maybe not and the shipping may kill it

Jim
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Old 11 February 2009, 08:24   #18
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Jim

As you can see from the pictures the trailer is built using an existing front 'triangle' of angle with the parallel rails added. The rails are 5.5m in length and the rib hull is 5.3m

As this is the first trailer I have built I was going to fix the rear cross member first (say 9" in from the rear end of the trailer rails) using the measurements from an existing trailer I have seen with the same size rib, and then work forward adding the 4 crossmembers with keel rollers at about a metre spacing and then add a fifth crossmember with a bow catcher 'V'. The winch post etc can go on the angle iron frame.

I was thinking of doing it this way rather than build from the front as I have plenty of space at the front to play with in terms of length but the boat needs to be as far to the rear as possible. At the moment the trailer looks like it will be about right in length. I shall also try to get the keel rollers positioned so that the hull clears the axle by 1 - 1 1/2", is this too close?

Unfortunately the tools I have are two angle grinders (one large and one small), a tape measure and a welder so swinging frames are not an option

Towing etc is not really a popular sport here and there don't appear to be any set rules. For example you cannot get a numberplate for the trailer as the Police control issue and will only give you two for the car. The accepted rule of thumb is that you have a second car follow you with his hazards on. There is no rule to say you must have lights on a trailer so people tow at night with without a following vehicle.

Thanks for your observations I shall keep chipping away.
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Old 12 February 2009, 05:28   #19
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Jim

As you can see from the pictures the trailer is built using an existing front 'triangle' of angle with the parallel rails added. The rails are 5.5m in length and the rib hull is 5.3m

As this is the first trailer I have built I was going to fix the rear cross member first (say 9" in from the rear end of the trailer rails) using the measurements from an existing trailer I have seen with the same size rib, and then work forward adding the 4 crossmembers with keel rollers at about a metre spacing and then add a fifth crossmember with a bow catcher 'V'. The winch post etc can go on the angle iron frame.

I was thinking of doing it this way rather than build from the front as I have plenty of space at the front to play with in terms of length but the boat needs to be as far to the rear as possible. At the moment the trailer looks like it will be about right in length. I shall also try to get the keel rollers positioned so that the hull clears the axle by 1 - 1 1/2", is this too close?

Unfortunately the tools I have are two angle grinders (one large and one small), a tape measure and a welder so swinging frames are not an option

Towing etc is not really a popular sport here and there don't appear to be any set rules. For example you cannot get a numberplate for the trailer as the Police control issue and will only give you two for the car. The accepted rule of thumb is that you have a second car follow you with his hazards on. There is no rule to say you must have lights on a trailer so people tow at night with without a following vehicle.

Thanks for your observations I shall keep chipping away.
If it clears by 1" there should not be a problem provided the bow can't dip when launching etc the lower the boat a bunked trailer the less depth of water you need to float it on or off

Are you going to weld the cross members to the rails or bolt them on and will your bunks be adjustable to set the trailer up for the hull shape.

I'd bolt the cross members under the rails with U bolts so you can set the trailer up to the boat, then when your happy you can aways weld them into place

Jim
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Old 12 February 2009, 06:48   #20
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... the lower the boat a bunked trailer the less depth of water you need to float it on or off...
I agree. Unless you've always got deep water, get it a low as possible. Your wheels look quite large diameter and since your axles are straight across the trailer, this is going to limit you to quite a high rig for bunks. Is there any way you can V the centre section of the axles?

Why do you guys angle the vertical spacers between the rails? Is there something I should know?
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