Trailer modding to suit a SIB

[ToniH]

Hi,

Here is what I am working on. My trailer is best suited for glassfibre and aluminum boats - not so much inflatables. So, I must mod it to suit my SIB a bit better.

Main problems:
1. rollers really do not handle the SIB gentle enough
2. front rubber bit also more suitable for other kind of boats
3. fender steps too sharp

#1 being the biggest problem.

So, first of all I swapped the front V-rubber to slightly less agressive one. Still going to add some neophere or something to make it softer. Old and new rubber together:

Then the fender step part, got to get some soft stuff to cover this:

And then to the rollers and the actual platform for the SIB.

First of all, start up point:

1st step: remove rollers and the part that flips up:

Then try to figure out the correct level for the wooden frame and rails:

And then draw up a plan:

I've never hauled SIBs with a trailer before so I am not sure what is the best solution for this. I have examined all inflatable trailer pictures I've found in the forum and basing the basic design on what I have seen.

Should the wood rails be covered with some protective or more slippery material?

So, all comments and suggestions are welcome.

 

[likalar]

Re: Trailer modding to suit a SIB

Your plan looks like a good one. Yes, carpeting on the wood will help reduce chafing wear on the boat bottom as the boat and trailer vibrate together over rough roadways.
A piece of carpet-covered marine plywood could be custom cut to line the inside of the fender/step assembly (see picture). Good luck,

Larry

 

[Sea Rider]

Re: Trailer modding to suit a SIB

What is you sib brand, lenght and width, how wide is your current trailer at middle frame to frame after having removed all unwanted rollers ?

 

[ToniH]

Re: Trailer modding to suit a SIB

Boat: 360 x 175 cm (12 ft x 5.8 ft).
Trailer width between fenders: 170cm ie 5.6 ft

If I lift the rail level another inch it will clear the fenders completely.

What kind of carpet would be ideal?

 

[likalar]

Re: Trailer modding to suit a SIB

What kind of carpet would be ideal?

The sponsors of this site sell the precut bunk carpet. Here's the link below: Or you could improvise with some indoor/outdoor carpets sold by the foot or even some strips cut from "welcome mat" carpet from home depot, OSH, etc.

http://www.iboats.com/Dorsett-Bunk-Carpet/dm/*******.858478201--**********.525850639--view_id.38426

 

[ToniH]

Re: Trailer modding to suit a SIB

Thanks for the tip. I live in Europe though but I guess I must ask what is the freight on 4 rolls of "bunk carpet". I don't know where to ask for such carpet here. Inflatables are rare and almost nobody makes/mods trailers for inflatables so no need for such product. It might be sold as something else but I don't know what to ask for to get the right stuff.

I must look into the carpet material they sell for busineses. You know the soft ones that wipe your shoes clean when entering a bank, store etc? They are sold by the meter so that could be one option.

 

[Sea Rider]

Re: Trailer modding to suit a SIB

Now that you finally have removed all unwanted parts as middle & lateral rollers, you need to add 2 wooden flat beds on each side, to modify structure and make 3 deep V angles in middle of each support will be time demanding and probably expensive.

Make beds some 5 cm less wider than tubes, place 2 square metal supports on each end of bed and give proper height as to have inflated keel on middle trailer including engine on transom. Probably will need to remove lateral shock absorbers, will do fine just with lateral springs.

Your rear final trailer look will be like last pic, but flat beds will be much higher to compensate for the inflated keel issue, a much better to have option instead of loosing precios time doing by the beach, lake, wherever. If sib still is slight wider than trailer, will need to remove fenders and re arange lights at back trailer. Can place any medium thick high transit carpet well glued on beds, if plain, better.

Check pics for better understanding.

Happy Boating

 

[ToniH]

Re: Trailer modding to suit a SIB

There is some restrictions on what I can do. Its registed as it is so I cannot change the structure of the trailer. Ie. cannot remove shocks, cannot remove fenders (fenders are must in any roadgoing trailer or vehicle) and cannot do any changes to the frame itself - other than add stuff.

I can legally build a trailer from scratch after my own design but that is not practical in this stage. Also currently I have no access to a welder so woodwork is basically what I can do. Also I want to be able to restore the trailer to its original condition if necessary for trailering "hard" boats.

I am contemplating about replacing the center roller assembly. I started thinking situation where I have no access to a ramp. The center piece tilts so it would make reloading easier. I would need to make the wood structure high enough so the keel would not rest on the rollers when the SIB is loaded. I also could cover the rollers with neoprene or same carpet material I will use with the rails. The rear extesion roller part also works as engine support.

Lets see if it works. Try to do some mock up with wood today if this thunder storm goes away.

 

[ToniH]

Re: Trailer modding to suit a SIB

Sea Rider, on your example the SIB is resting only on its pontoons and transom. Is this ok or should i try to align the rails so that also the inflated keel is supported?

I can make the rails that support the pontoon 2x wider than in my original plan. This would help in aligning the boat. I think in can find some L-shaped brackets or even bend some alu pipes to make side supports like likalar suggested if necessary. I also have the marine plywood for this.

I already bought enough 2x5"s for the project. Quite heavy stuff but I estimate that the structure (~24m at 2.5kgs/m) will weight no more than 60kgs (132lbs). The trailer has max capacity of 560kgs (1235lbs) so I will be at less than half of max capacity when everything is loaded. Boat 80kgs, motor 33kgs, gas + gear 50kgs + carrier structure 60kgs = 223kgs.

 

[Sea Rider]

Re: Trailer modding to suit a SIB

Tony,

OK if you have lot's of legal restrictions, both tubes rests on bunks and transom & engine on rear horizontal frame, that's because this sib is crane wiched to from sea, but if used at beach is just a matter of raising higher the front trailer so that keel passes without problem by rear frame & support, same when removing from water. The bulks only support boths horizontal tubes before both turns to form the bow, make a removable support on bow. Do not make bunks supports wider than wooden bunks, just bit less, if better, use all 3 laterail rails, so each one has it's own under bunk support, all at same heights and buks at 180?.

Being your sib slight wider than available lateral space, and as you cannot remove fenders the only option to go will be raised bunks as to have inflated central keel passing slightly touching rollers. Inflate tubes & keel to 3.5 psi, that will give the correct bunk height to go for.

As you will have deep V bunks on back trailer's rear frame, will need to keep sib well inflated if thinking in having engine placed on transom at all times, including road towing issues. My sib is living on that simple, versatil low cost trailer for the last 2 years constantly towed with no tube/transom/engine issues, but kept well inflated, shaded and covered.

Can re arrange rear roller height to support under transom. Will have sib/trailer configuration as this pic, but with wider bunks supporting middle sib tubes & engine If trailer axle is movable, adjust as to have max 30 Kg weight on ball/tongue if using up to a medium compact car size.

Happy Boating

 

[ToniH]

Re: Trailer modding to suit a SIB

Got a break in rain and spent quick 90 minutes of measuring and sawing the 1st version of the railing. So here it is.

Its not high enough to completely clear the fenders (about 1" too low). I need to think whether to rise it or make the side protection likalar suggested.

Also, with the beam in the back being full width the tilt up center roller thing probably has not enough room to work. Must figure out what to do about it.

Comments?

 

[ToniH]

Re: Trailer modding to suit a SIB

OK, tried to lift the bunks another 5cm (2") but IMO it makes the platform too high for practical use. So, I modded the rear beam so that I can refit the tilt without making the whole thing higher.

I am thinking of making a solid soft and slippery cover for the middle rollers so the boat can slide on top of that instead of touching the rollers. Also the front wooden beam would require some kind of soft cushioning.

The 2 outer bunks on each side are now located so that the gap between them is in middle of the pontoons. This allowed bigger gap between bunks and fenders - more space for fender cushion. Should I close the gap between bunks altogether?

The 2 inner bunks are there just because I didn't know what to do with them.

I have a difficulty that I cannot get help for lifting the boat on top of the trailer at this time and obviously cannot do it alone. So I cannot really test fit it without actually assembling it. This is a shame as I know the bunks will be in wrong position for sure.

Maybe I should just screw in the outer bunks and hoist the boat on top of them? And then try to figure out where to position the inner bunks (sidewise and elevationwise)? What would be the best position for them? Under the aluminum floor rails maybe?

So, here is the second version:

EDIT: noticed that the bunk height compared to fenders looks totally different in these 2 last pictures but its actually the same. Its different side gap + camera angle thing. The bunk is 3cm (1.18") below the fender top.

 

[Sea Rider]

Re: Trailer modding to suit a SIB

Having a central gap or not having any won't make a big difference as you will have a carpet on them, right ? Personally would remove 2 central large wooden slats as these will rub against inflated kee when trailer is towed. When placing inflated sib resting on both lateral slats that forms the bunks, is outside main tubes resting against fenders ? If so why don't you have bunks at same height as fenders, my trailer having inside tires is far way higher that having tires at lateral trailer frame.

Sib's central keel once inflated, must not rest on top of anything, must be completely on air. Tomarrow will post more pics of under sib/trailer to have an overall best performer idea.

Happy Boating

 

[ToniH]

Re: Trailer modding to suit a SIB

After surfing the web some more I am starting to get the picture that a SIB should be supported on a trailer by its pontoons (tubes) and transom but not so much by its inflated floor/keel? Is this correct? Can I forget trying to figure out where to support the floor and just make a good platform for the tubes and transom? Would make my life much easier.

 

[ToniH]

Re: Trailer modding to suit a SIB

as you will have a carpet on them, right ?

Yes, ordered some suitable carpet today.

When placing inflated sib resting on both lateral slats that forms the bunks, is outside main tubes resting against fenders ? If so why don't you have bunks at same height as fenders

That is a good question. I don't know as I haven't been able to test fit it. With the rollers it didn't but I don't know how its now.

I didn't make the bunks the same height as the fenders because I felt the whole setup becomes too high.

PS. I am wondering that if I would install the bunks in an angle the tube should clear the fenders for sure. I mean like this: bunks in angle

 

[ToniH]

Re: Trailer modding to suit a SIB

Sib's central keel once inflated, must not rest on top of anything, must be completely on air.

OK, thanks for this clarification. I surely must make my bunks higher to achieve this. Or at least the front of them.

 

[Sea Rider]

Re: Trailer modding to suit a SIB

Some more tech ideas:

1-Rear & front bunk must be same height evenly on trailer, raise enough so that inflated keel is air suspended not touching anything. This also will free rubbing space on lat tubes against fenders.

2-Bunks width, al least 15", extend rear bunks to the beginning of cones.

3-Once my trailer is horizontal, has 26" from floor to upper bunks (where sib rests), ideal is to have a certain height, better for your back to work on a higher bunk, with trailer well axle balanced you can do wheelys, perfectly for rinsing inside to remove sand/debris from deck, just open water valve and drain completely.

4-Do not extend interior keel bunks larger than 2", if more will rub against formed keel tent on it's sides deteriorating bottom fabric.

Happy Boating

 

[ToniH]

Re: Trailer modding to suit a SIB

Thanks again for the tips.

I today made a test assembly and hauled the boat on top of the trailer. Not very easy alone and on dry land.

I installed the outer bunks in an angle (1st picture) so they will support and direct the tubes away from the trailer fenders. This worked well.

But, as expected the front is not high enough. The front keel makes a contact with the trailer and the front lateral support beam. I must rise the front maybe 3" to be sure there is no contact. In 3rd picture below there is an extra beam visible which I used to check how 2" rise will effect.

The height from ground to upper bunks is now 26.7". Bunk width is about 12", this seems to support the tubes ok and does not touch the keel at all.

I also need to move the winch stand forward so I can move the boat a bit more forward too to get the bunks all the way to the cone beginning like you said. This will establish the correct transom support position too (2nd pic).

 

[Sea Rider]

Re: Trailer modding to suit a SIB

Definitely not easy to place a sib on trailer top if alone, that's why boating requires at least 2 mates

Final modifications looks good, will need to re arrange these:

Place wood A underneath B on top of D, move D to E, just support straight tubes portions, cut where tubes begins to turn to form bow. Both tubes portions must rest evenly on bunks at 180?

Happy Boating

 

[ToniH]

Re: Trailer modding to suit a SIB

Wood A is there only for me to figure out correct height so that the keel would not touch C. So, I just put it there when I saw the keel would not clear C. I will place it on top of C (not full widht of the trailer but in 2 pieces so it will not interfere with the keel).