Supporting the tubes or floor of a SIB?

MrHeadsocket · 25 December 2014, 21:30

I'm getting ready to sort out my trailer (at long last!) from the single deck that the SIB sits on to a proper set up putting no strain on the transom or floor (the deck of the trailer actually causes the floor to bend due to the weight being on the inflatable keel and having a 50kg engine!) My designs are either supporting the tubes or supporting the join between the floor and tubes. What's best? Obviously I will have transom support (possibly roller bunks to to support and guide the front onto the trailer) but which bit should I support, the seem or tubes or both if I can? I will post some designs tomorrow but have attached a picture of the current trailer. My budget is about £100-£150 for materials, I already have the tools

cheers in advance!

camelgas · 26 December 2014, 08:25

On a budget, I would:
Buy 3 treated 100x50 C16/regularized timbers min 1m longer than the boat and use them to support under the tubes and the third under the keel, make metal brackets to the existing trailer as needed. Bolt or weld on and coach bolts to the timber, cover the three bunks in cheap industrial cord carpet. Remember a metal tie down/winch post at the front center.

With the off cuts of timber: make a profiled piece that fits under the transom and takes all the weight of the motor, cover in carpet, fix to trailer.

I did this to a unsuitable trailer that came with a SIB some years ago, its worked out great and gives good support, 400 mile round trips have been no problem.

jyasaki · 26 December 2014, 08:28

I'd avoid rollers on a sib. They put too much stress on a single point. If you need to guide the boat on, use upright side guide-on bunks

IMO the best support point is, as you mentioned, the tube/floor interface. The hard floor hits the fabric at that point, so you are less likely to stretch anything. If you need more support, a single flat bunk under the front of the keel should do the trick. The back is unlikely to need more support than just the transom.

You will probably want to be able to lock the motor's steering to keep it flapping around in turns. I like triangulating the motor to the trailer to keep the fore-aft pendulum action to a minimum, but that seems to be a hot button issue on here.

Keep updating as you decide your course;

jky

Seaflyer02 · 26 December 2014, 17:02

Once done always remember to strap it down so it cannot bounce as you trailer it, especially the engine/transom.

MrHeadsocket · 26 December 2014, 17:31

Cheers for all your advice! I had a design on my computer but it crashed before I saved it! -_- so will redo and upload

I will have a couple of designs, one supporting the tubes and one supporting the seems between the floor and tubes... it will have tie down points for ratchet straps and a transom saver attachment type thing

MrHeadsocket · 26 December 2014, 18:09

Below are 2 designs as well as a drawing of the trailer with no modifications once the wooden deck has been removed. The trailer does have a winch post already but the winch could do with replacing (perhaps one job at a time!) which of these designs do you recommend and is it legal to have the supports (of design 2) over the wheels? The boat tubes sit over the wheels anyway and have never had any problems with the Police.

With both designs, the beam of wood across the trailer at the front would have a cut out for the keel (see below, "Cross Section") and Design 1 would obviously be more simple to make whereas Design 2 would be more complex (but not out of my skill zone) but it means that the trailer would have to go further into the water as the supports would be higher due to the extra beam across to support the wider beams. Also, would I have to add anything else? I am usually in the boat for launching and recovery whilst someone is backing the car down the slipway, so would these be stable and strong enough?

camelgas · 26 December 2014, 18:55

I do not like rollers for inflatable keels (support reasons), replace these with a center bunk add a few braces (triangulation) to stiffen it up and I recon your there.

MrHeadsocket · 26 December 2014, 20:50

Awesome! Will go with design 1 as it is simplest. I will remove the current keel rollers and once I have assembled everything I will add the central bunk

jyasaki · 27 December 2014, 00:00

Quote:

Originally Posted by MrHeadsocket

I will have a couple of designs, one supporting the tubes and one supporting the seems between the floor and tubes...

If your trailer only supports the tubes and you have a tube get cut/scraped/rammed and burst, you may find yourself unable to get the boat home.

In the summer you may find yourself needing to relieve tube pressure when going from cool water to a warm sunny road. Air expands as it heats up, so I typically trailer with just enough air in the tubes to hold their shape (well, in summer, anyway. Cold and rainiy isn't an issue with this.) Yields the same problem as above.

jky

MrHeadsocket · 28 December 2014, 15:54

After a day of working on my trailer, inflating my SIB and getting the 50kg Yamaha out of it I have a blank canvas. But it does need one hell of a sand! Obviously if I could afford a new trailer I would get one but needs must! So Tuesday I will get the materials, any tools and measurements and commence! Will keep you guys updated.

camelgas · 28 December 2014, 16:43

once you have got rid of the loose rust and cleaned all the metal work down , use Galvafroid paint it has a high zinc content and will help keep rust at bay !.
Also remember to use A4 stainless fixings if its going in the sea.

hippyhunter · 01 January 2015, 00:09

Galvafroid's good stuff, it's not cheap and the tin's really heavy because of all the zinc in it.

I'd concentrate on supporting the tubes and transom while you tow the boat, to be fair it might be worth sticking with a flat trailer and letting some air out of the keel when on the road.

If you're towing with the (50kg) engine on the boat it might be worth thinking about supporting the transom or the leg.

Jim

MrHeadsocket · 04 January 2015, 17:16

Got some better pictures of the trailer stripped! I've been taking some wet n' dry paper to it to get some of the surface rust off! I'm not going to go with expensive stuff for the paint as I can't see me using this trailer after 2015, and I won't be using it much anyway this year (at most it'll be used 20 times) hence why I'm not going to huge efforts. I will be saving up for a new trailer for the SIB.

I've got a design now, two bunks, one on each side and then two new bunk posts to support the transom (where the existing ones are, which will be replaced), and a transom saver that slots into the chassis on the trailer to take the engine leg. But it occured to me that it's not good to stop the bunks short of the transom as that could cause bending. I had a counter arguement (from my father who is helping me with this build) that it would be unsafe to tow the trailer with the bunks extended past the transom as the wood could bend and snap... but the axle can be moved back to prevent this (as the bunk supports are welded to the axle). What are your verdicts? The wood I'm using is C16 treated timber that is 3600x45x75mm which will be covered in bright green cord carpet as suggested.

slate1234 · 04 January 2015, 17:34

You may be better useing non treated timber I'm sure I have been told somewhere /been on a job locally and the copper used in treated timber should not be used with galvanised metal or salt water the copper used in the treatment can cause a reaction, just a thought to bear in mind.

MrHeadsocket · 04 January 2015, 17:36

These are the bunks I plan on using for the transom:
Pair Of Side / buffer channel bracket & Rubber Bunks,300 stems boat trailer Part | eBay

And to attach the clamps I will be using this fitting kit (designed for jockey wheels but oh well):
Jockey wheel clamp fixing kit for trailers & caravans | eBay

However the bunks are out of stock at the moment. Would there be any harm in using these instead?
2 X Parallel side roller bracket, roller, 440mm Stem And Clamp For Boat Trailer | eBay

Or are rollers a definate 100% do not pass go do not collect £200 don't get them for SIBs?

jyasaki · 04 January 2015, 18:21

2 long bunks running just inside the tubes, and extending beyond the transom will work fine. Maybe another center bunk to support the front at the keel line before the bow rise.

Not sure how you plan on using the roller things you just posted. Those (I believe) are designed to be mounted vertically along the freeboard to keep the back of the boat centered on the trailer in wind or current.

jky

MrHeadsocket · 04 January 2015, 18:46

Quote:

Originally Posted by jyasaki

2 long bunks running just inside the tubes, and extending beyond the transom will work fine. Maybe another center bunk to support the front at the keel line before the bow rise.

Not sure how you plan on using the roller things you just posted. Those (I believe) are designed to be mounted vertically along the freeboard to keep the back of the boat centered on the trailer in wind or current.

jky

The bunks/rollers if I didn't have the bunks extending past the transom would be used to support the transom, they would be in place of where the old ones are on the back of the trailer (see the above pictures)

jyasaki · 05 January 2015, 05:58

So mounted crosswise under the transom? You'd have to be pretty precise with locating the boat on the trailer.

You don't need to support the transom across its width (as it's not going to flex); you need to support it relative to the rest of the boat (as the motor hangs off of it and not supporting it puts stress forward.)

jky

MrHeadsocket · 17 January 2015, 14:36

Just thought I'd update! The bunks under the transom idea has gone, the transom will be aupported by the bunks going under the floor. I've been sanding the trailer down but the rain has been slowing my progress

I've also bought two new dust caps for the hubs but can't for the life of me get them on, full of grease or not! I've tried tapping them in using circular motions, and all sorts! They measure 50mm, same as the old ones and the ad even said they were suitable for most 1" taper hubs! Any ideas? Hopefully will be cracking on with the trailer again very soon!

camelgas · 17 January 2015, 15:43

I rebuilt one of our club trailers over Xmas and had the same problem,
I put a taper on the leading edge of the cap with wet and dry. It then tapped in with a block of wood and was a snug fit.
Snow and cold has slowed me up a bit today, the joys of working out side year round.
I love it really !.