What happens if I fix my sib's floors?

[berat]

This is my first season with my Zodiac MK3 Grand Raid 1986.
My stingers is from wooden and has some crack on it, and there is too much bending and streching on the floors during the cruise.

The question to experts is What if I fix the first 3 floors with an aluminium pipe (dia:40mm 5mm thickness).

According to your valuable comments thinking about to fix the 4. floor and carry up the floors to the tubes as you can see in the pictures. The red line is the aluminium pipes screwed to the floors.
The black lines are the flat ropes that tenses the pipes and connected floors to the tubes.

Note: I roll up and carry my sib almost never in a year

[steco1958]

Before making any changes to the way you fix the flooring, make sure you have the tube pressure correct, both before you get in the water, and after approximately 1 hour after the boat has entered the water.


Always keep tubes at optimum pressure, as this aides the job the stringers are doing !!


Steve

[jyasaki]

Originally Posted by berat

My stingers is from wooden and has some crack on it, and there is too much bending and streching on the floors during the cruise.

The question to experts is What if I fix the first 3 floors with an aluminium pipe (dia:40mm 5mm thickness).

Aluminum does not do well with any repeated flexing. Eventually it fails due to stress cracks.

Better to address the cause of the flexing first (likely your solution is in the post just above) and see if that cures your problem.

But, if you do go the bracing route, rather than tubular, I'd look for something like an extruded I-bar, which will have less flex for a given force. Should last a little longer.

jky

[jeffstevens763@g]

Have some new stringers made from wood will be better not a big job for a carpenter

Cheers

[berat]

steco1958 Hi Generally my mistake can be inflate the tubes on the hot sand and then never check the pressure on the water. I'll check it thanks

jyasaki Hi I'check the pressure if it continue to bend I have to fix the first 3 floor with tubular which I have already had. I looked for sigma profile but could find the tubular pipe.

jeffstevens763@g Hi I showed a sample stinger to a carpenter to get a prize, that was a lot more than original aluminium stingers

[Fenlander]

Berat if you put the tubes on top of the floor in place of the stringers which should be on the side you will find the floor edges with no stringers on are very sharp so could wear through a tube.

So you need to leave the stringers in place with the tubes as reinforcing... and repair the cracked one so it can't damage the tube.

[idsebby]

Go to a machine shop and get some aluminum folded into a triangle. It should not cost much to make some. I had some made for my new wooden floor. I reckon a place would not charge more than 70 for the two stringers.

[The Gurnard]

My thoughts are slightly different from some of the other guys..so take them with a pinch of salt if you wish.

I use my wooden floored 4.3m Sib in any weather..therefore I know how much a pounding the floor gets in a good chop. There is no way I would trust home made repairs to my stringers. If they break at sea in a bad weather day..and even the best can get caught in one of those days.. my boat would then be very unseaworthy..especially if sharp splinters of either wood or broken ali went through the tubes.

For me.. my life is worth the cost of buying the proper replacement part.
However if your use is only calm waters and not far from the shore..its a different kettle of fish. However if you do get caught out.. and a bit further from safety that you hoped..remember ... those who recommend making stringers..will be safe on land

[jeffstevens763@g]

Look up alibaba.com extruded aliminium showcase if you contacted them they will possibly have your profile and maybe end caps to suit.

[idsebby]

Originally Posted by The Gurnard

My thoughts are slightly different from some of the other guys..so take them with a pinch of salt if you wish.



I use my wooden floored 4.3m Sib in any weather..therefore I know how much a pounding the floor gets in a good chop. There is no way I would trust home made repairs to my stringers. If they break at sea in a bad weather day..and even the best can get caught in one of those days.. my boat would then be very unseaworthy..especially if sharp splinters of either wood or broken ali went through the tubes.



For me.. my life is worth the cost of buying the proper replacement part.

However if your use is only calm waters and not far from the shore..its a different kettle of fish. However if you do get caught out.. and a bit further from safety that you hoped..remember ... those who recommend making stringers..will be safe on land

Should have explained my wooden floor was made of fiber glassed layered 1in marine ply.

[The Gurnard]

Originally Posted by idsebby

Should have explained my wooden floor was made of fiber glassed layered 1in marine ply.

Sounds like a nice solid floor idsebby..far more robust than my quicksilver wooden floor..

however IMO the subject is stringer strength and not floor strength. I can only imagine the join between the floor panels is the weak link ..and that is why the stringers are there.?

Perhaps more useful for berat’s issue .. is to add the thickness..and sizing of the aluminium stringers that you had made ?

They form the main structural part for the longitudinal strength of a SIB ? I appreciate the tubes at correct pressure provide a good part of that strength..but I am under the impression the stringers are of a shape .. which is pushed onto the edges of the boards by the tubes. Properly assembled ...there is no movement whatsoever between floor and tubes..due to the carefully designed shape of those original stringers. Movement of the floor in heavy seas.. could cause accelerated wear on the tube surface..

Use to weak a material for stringers and if they snap (at that weak point on the floor joins)..could very well puncture tubes at sea.

I confess ..although Im a great DIY person .. a couple of hundred pounds for a main component in a SIB is nothing to me .. I spent more replacing my broken mobile phone last month.

Just my opinion..and is a valid as anyones . ..but I felt it worth mentioning what could happen if the stringers broke out in heavy weather.

[idsebby]

Is your keel at full pressure. This is what keeps the floor in place as it pushes it up agains the other tubes. Most of the time the keel leaks in these and causes the floor boards to jostle. There was some one on here a couple months ago that was giving away a floor but they posted it in the rib side of things.

[idsebby]

Didn't know how to post the url from my phone so here is the post.

[berat]

Thanks guys for all advices and worst case scenario. I cant take that risk of broken stinger went through the tubes. I ride the boat sometimes more than choppy water like 4~5 bofor. That sounds like terrible.
I dont want to be a guy DIY things on the boats because I should be in the water in that times, i work too much
I cant find proper or original stingers in my country, so I decided to add these aluminium pipes.
Here is my stingers, i dont know if you can see the fractures

[The Gurnard]

Originally Posted by berat

. I ride the boat sometimes more than choppy water like 4~5 bofor.

You too will be fully aware of the pounding the floor takes in rough weather berat .. Im also certain you will have the experience to know the strength of material to repair the boat...more than some folks who may just use SIBs occasionally for recreational use on good weather days

I cant see the fracture marks in the small photo.. but I would take Fenlander’s advice and try to repair them enough to keep them in position in the boat. While Im fully aware the pressure keel also helps keep the floor in position.. the stringers IMO are very important for that purpose..and is why they have the profile they have.

If the stringers are wooden.. and I couldn’t get replacement ones .. I would fill the fracture cracks with waterproof wood glue.. clamping everything tight shut until set .. then perhaps protect the area with a thin sheet of Aluminium attached to the outside at the fracture points..(similar to the ends I see already on the stringers.) This will be for tube protection only..if the stringers start to splinter again. Then replace the stringers in the boat. The stringers are obviously still weak so they are now only there to stop floor movement against the tubes.

The main strength of the floor joins will now have to come from your home made stringers attached to the floor as per your idea with the ali pipes that you have. Perhaps I would use stout 2” x 2” wood battons if available as they may be easier to secure to the floor than your pipe ? However .. whatever you use for the DIY stringers.. there is plenty room in the floor to add more than one each side..assuming you think its required. Over engineered or too many stringers will do no harm.. but under engineered stringers may bust in those seas you know and work in

Good luck with the repair..I think you have things well thought out for the materials you have easy access to

[Quicksilver mike]

When I bought my boat i had a similar problem, the boat didn't come with any stringers. After taking advice from guys here on the form i decided against having timber stringers made and after emailing a lot of marine shops managed to track down a set of stringers.

I got mine from:

South Eastern Marine Services Ltd
Incorporating SEMS Aerosafe.
25 Olympic Business Centre
Paycocke Road
Basildon
Essex
SS14 3EX
Tel 01268 534427
Fax 01268 281009

[idsebby]

By the looks of those stringers the easiest and quickest thing to do would be to find aluminum flat bar about 4 to 5 mil thick. Then screw and glue it on to the stringer. This will give you the extra support and keep the wood from splintering. Obviously counter sink the screws. After this you could wrap the whole thing in hypalon or a cheaper strong fabrics to keep it from splintering into the tube. By the time those crack enough to splinter into the tube the boat would be folded in half, And well you probably will be in the drink.

[jeffstevens763@g]

I agree with gurnard I carnt see the cracks but wood is a living material and will dry and crack, funnily enough I was looking on YouTube at a master boat builder in USA refurbishing a wooden fishing boat he was doing exactly what gurnard's suggesting and glued the timber up, those stringers are very robustly built as I see them so a good rub down repair as said and varnish should sort them out make sure the boat is inflated properly to support the stringers.
If they were mine I would support them at each end and try some weight in the middle to see if they crack or cracks open up to test there strength.

[berat]

Thanks guys. I didnt post for a long time. I m depressed becuse of my floor is seperated two times and i dont use my boat too much, i dont trust it clearly.
I m thinking (actually dreaming) to replace the the floor with a rigid bottom if it is worth to what it costs. There is too many used fiberglasss bottoms without tubes in my country and if i can find compatible one with a resaonable price gonna work on it.
In other way its floor will be reassembled or changed and i keep in my mind your valuable ideas and comments.

[idsebby]

Just put a solid piece of marine ply on top of it. Make it one whole part.