Thread: Ramp

Yes Harry, easier no doubt. Cheaper, mm ... hardly. Last time I checked they wanted 10,000 for a 5 meter one.

Having said that I did send an email again asking for a quote to make just the metal structure without the wooden floor.
Lets see what they come up with, but I am not holding my breath.

My welding experience was limited to steel, but with assistance from an experienced friend we set up and welded together a pair of substantial pontoons for a project. Cutting discs for ally are available and work well. Yes we had to replace wire feed wheels and liner, and buy in argon, but the actual welding while not pretty, was sound enough and no more difficult than steel, using material between 3mm and 6mm thick.
Just need to work out whether your machine has enough output to handle a suitable wire gauge within its capacity. Can not advise on that, and admit that we had a larger machine at our disposal, but recall that we were still at the lower end of its capacity. No real problems. Just need to de-oxidise weld areas with a (powered) wire brush or ally cleaner before welding and it will go well. Regards,
Combustor.

Hi Marc,

For your Aluminium RHS etc. you can look at Edcon Steel as they have a good range of Aluminium Products.
For the Cutting of the Aluminium it depends on what you have available, e.g. Cold Saw, Bandsaw or even a Drop Saw with an Aluminium Blade, at worst depending where in Sydney you are you can bring it around to my place and I can cut it for you.
As for the Welding ask a good welding shop, someone like Silverwater Welding Supplies who can advise you on whether your setup can handle the job and what you need to get to do it. You can always shop around for a Welder to do the welding and as you will have it all pre-cut all they have to do is the welding saving you on cost. I have TIG etc. but no experience on welding Aluminium so I cannot help there at this time.
You have the plans and can use that as your basis for your design also looking at what can be sourced as off-the-shelf to complete your project.

Keith_W

Hi Keith and thank you for your generous offer. I do have a cold saw though and my project is a bit further away from your location. Thank you anyway!
I shop at Edcon steel all the time, did not know they sell aluminium.

Good news on this project. I took the boat and went for a wander around the neighborhood looking at the pontoons and their ramps. Some of the new ones have ramps about the size I need and they all have very small sections of steel and no handrail. I didn't go under the ramp to have a proper look since it was Christmas day and the place was crawling with people who took exception at me driving really slow checking out their pontoo (woohoo I am going to wear it out) but to me it looked like 100x50 or so. Ill go and have a proper look during the week when there is no one around and measure the sections. I can tell the thickness from the radius of the edge.

May be I can get away with a very simple build in steel not the monstrosity i was thinking of.

Hooroo
Marc

Several good points raised in this thread.
As I see it, your constraints are as follows:

• Sectionalised construction for installation
• Long term corrosion resistance
• Cost
• Weight both for installation and buoyancy of your pontoon
• Strength, both weight bearing and side loading from locating the pontoon, tidal/flood flows, debris impact and mooring watercraft.

The need for the structure to be broken down really does favour channels rather than box sections. Box sections do not bolt together well, particularly in the thinner wall sections you will be using. The reason for this is that, unless the holes are sleeved or 12mm+ thick plates with tapped bolt holes welded on, (a lot of work and a PITA for installation), the section crushes long before any decent tensile load is achieved on the fastener. Box sections should very rarely, if ever be used uncapped.
I don't know what your access to site is like, but just remember that an empty 205 litre drum will support 150+ Kg safely, so perhaps a one piece construction with a drum strapped to each side on the connection end could be pushed off the bank and floated out to the pontoon, two hinge pins driven in and the drums then removed. You would either need to provide for ballasting the drums to align the hinge pins or have some adjustable straps to raise and lower the pontoon.
On the subject of ballast and buoyancy. I once built a pontoon for a school rowing club - designed by a Naval Architect no less. The pontoon floated fine and had ballast/buoyancy tanks to enable levelling and height control. The only problem was the walkway that the architect specced up weighed near on 5 tonnes including decking, (according to the load scales on the crane used to install it). Yes, it sank the side of the pontoon, below the water in fact - as we said it would, he mucked up his calculations and reckoned the entire structure weighed less than what we calculated for the timber decking alone. Solution? Lots of empty 20 litre plastic drums with the lid siliconed on, placed under the pontoon decking. Each one supplied 20Kg of buoyancy and slowly the pontoon rose from the water and eventually sat level. You may need a similar trick to compensate on your pontoon.

Corrosion resistance. Salt or fresh water use? Salt water really ups the ante as far as the degree of corrosion protection required. Bolted joints are a weak point, as are bolts, generally the first place rust is seen on a structure are in these areas. Galvanising is less effective in a salt water environment in my experience too. If you need box sections hot dipped, then either two v notches cut in all cap plates and sealed connections or two holes drilled in same will be required. Aluminium presents the need to use stainless fasteners, ($$$$$ and threads need to be lubricated when installing).
A left field option would be a good industrial coating. I used a coating once that was tougher than galvanised by a large margin. Colour choice and aesthetics could be an issue though.

Cost. I reckon Galvanised and Ally would be very close with the advantage to Ally if bolted joints can be avoided. Galvanising is rarely a cheap undertaking.
For you to use Ally, you would be up for a roll of 1.2mm 5183 or 5356 wire, a new liner, a cylinder of argon, some 1.4mm tips and you could get away with 1.2mm V groove feed rollers if you already have them. Not cattle stations in itself, but all added cost. A decent 250A mig will weld 3-6mm ally all day and night. Absolutely no need to go for a TIG welder, in fact TIG would be the worst choice for welding this structure - slow, softer weld and greater loss of tempering from the aluminium section. Pulse mig not required either - nice, but not neccessary.

Weight. One piece construction will always be lighter than sectioned construction. Your heaviest component will be the timber decking. Could be worth looking at expanded metal decking, particularly if you go all aluminium construction.
The lighter the structure for a given strength, the easier the installation and the more it can carry.
Also see earlier comments re. ballast and buoyancy, I guarantee that some adjusting will be required.

Strength. Is this pontoon installed in a tidal river? Do you have floods? What about debris like trees etc being carried by the current and impacting your pontoon?
At least put some diagonal bracing in the floor, but possibly consider a couple of guy lines. Load bearing strength is easy to achieve with the massive truss that the side rails provide. If you allow for 2 80Kg people per square meter then you will be on the safe side of life.

Overall, if it were me and other factors allowed, I would build a one piece, Aluminium structure out of box section and deck it with heavy expanded aluminium mesh or aluminium walkway mesh.
Apologies for the lengthy post.

Originally Posted by Combustor

My welding experience was limited to steel, but with assistance from an experienced friend we set up and welded together a pair of substantial pontoons for a project. Cutting discs for ally are available and work well. Yes we had to replace wire feed wheels and liner, and buy in argon, but the actual welding while not pretty, was sound enough and no more difficult than steel, using material between 3mm and 6mm thick.
Just need to work out whether your machine has enough output to handle a suitable wire gauge within its capacity. Can not advise on that, and admit that we had a larger machine at our disposal, but recall that we were still at the lower end of its capacity. No real problems. Just need to de-oxidise weld areas with a (powered) wire brush or ally cleaner before welding and it will go well. Regards,
Combustor.

Vinegar works well for cleaning ally, that's all my brothers use, for cleaning up boats prior to welding and after.
Kryn

Karl Robbers;

Several good points raised in this thread.
As I see it, your constraints are as follows:

• Sectionalised construction for installation
• Long term corrosion resistance
• Cost
• Weight both for installation and buoyancy of your pontoon
• Strength, both weight bearing and side loading from locating the pontoon, tidal/flood flows, debris impact and mooring watercraft.

Yes, you got it in one
After seeing other ramp commercially built, I'll go for steel RHS. All I need to determine is the correct section. I understand that sections can not be bolted straight through the middle, I can make a tenon out of flat bar in a U shape that slides right in the post and that can withstand the pressure of two bolts.

I don't know what your access to site is like, but just remember that an empty 205 litre drum will support 150+ Kg safely, so perhaps a one piece construction with a drum strapped to each side on the connection end could be pushed off the bank and floated out to the pontoon, two hinge pins driven in and the drums then removed. You would either need to provide for ballasting the drums to align the hinge pins or have some adjustable straps to raise and lower the pontoon.
It is actually much better than that. At high tide the pontoon is leveled with the top of the rockwall and so I can push the side sections to the anchor pins and slide them on. I will need a bit of a balancing act later to push both beams out with the pontoon and slide the anchoring bar onto both of them. Not easy but duable at the change of the tide when the water is still.

On the subject of ballast and buoyancy. I once built a pontoon for a school rowing club - designed by a Naval Architect no less. The pontoon floated fine and had ballast/buoyancy tanks to enable levelling and height control. The only problem was the walkway that the architect specced up weighed near on 5 tonnes including decking, (according to the load scales on the crane used to install it). Yes, it sank the side of the pontoon, below the water in fact - as we said it would, he mucked up his calculations and reckoned the entire structure weighed less than what we calculated for the timber decking alone. Solution? Lots of empty 20 litre plastic drums with the lid siliconed on, placed under the pontoon decking. Each one supplied 20Kg of buoyancy and slowly the pontoon rose from the water and eventually sat level. You may need a similar trick to compensate on your pontoon.

​Yes, I wouldn't like to get that naval architect to design a boat for me. ha ha. My pontoon is a commercial marina pontoon 6m x 2m, has 4 x 1200 litre tanks under it, aand it is rated for 2400 kg. The frame is 6"x2" aluminium and the deck is 6"x1.5" hardwood. When we get off the boat onto the pontoon even if 2 or 3 get on at the same time, it hardly lists at all. However the ramp according to previous calculations comes at 380k if deck is hardwood, 300 if treated pine. Half of that weight will be sitting on the edge of the pontoon adn will make it list a bit. i can not put water in the tanks because they are built across and have no dividers in side them. So I either add flotation on the ramp side or add weight on the opposite side. I'll cross that bridge when I get to it but I bet it will be way easier to make a few blocks of concrete sit on top of one end of the two central tanks then build a structure to hold a 300L tank.
http://www.marinedocksystems.com.au/
You can see my pontoon if you click on commercial pontoons on the lefto hand side menu, and then see the first picture down that reads Marina Walkway 6x2m

Corrosion resistance. Salt or fresh water use? Salt water really ups the ante as far as the degree of corrosion protection required. Bolted joints are a weak point, as are bolts, generally the first place rust is seen on a structure are in these areas. Galvanising is less effective in a salt water environment in my experience too. If you need box sections hot dipped, then either two v notches cut in all cap plates and sealed connections or two holes drilled in same will be required. Aluminium presents the need to use stainless fasteners, ($$$$$ and threads need to be lubricated when installing).
A left field option would be a good industrial coating. I used a coating once that was tougher than galvanised by a large margin. Colour choice and aesthetics could be an issue though.
The river is brackish water at 6g of salt per litre as opposed to 35g per litre in the sea. I repaired an old jetty that was falling apart and kept it going for 4 years with lintel material pushed in the mud and all the way up to the bearers. The section in the mud did not suffer any corrosion, the one in the water started rusting after just 2 years yet the section above the high tide mark had the galvo in very good nick. It seems that a galvanised section of steel will do well providing it is not in the water. having said that, I plan to paint the hot dip galvo with a two part epoxy paint made for that purpose. I have to ask the galvanising place not to give the job that final coat/bath they give it that makes it hard to paint. As far as the need for holes, do you have any idea of the size holes we are talking about? If I cut two holes at each end say 16mm would that be enough? i can always cut a thread in each hole and plug it with a short bolt and some silicone.

Cost. I reckon Galvanised and Ally would be very close with the advantage to Ally if bolted joints can be avoided. Galvanising is rarely a cheap undertaking.
For you to use Ally, you would be up for a roll of 1.2mm 5183 or 5356 wire, a new liner, a cylinder of argon, some 1.4mm tips and you could get away with 1.2mm V groove feed rollers if you already have them. Not cattle stations in itself, but all added cost. A decent 250A mig will weld 3-6mm ally all day and night. Absolutely no need to go for a TIG welder, in fact TIG would be the worst choice for welding this structure - slow, softer weld and greater loss of tempering from the aluminium section. Pulse mig not required either - nice, but not necessary.

It is clear that Aluminium is the better material choice, but it is also clear that it will be yet another challenge on top of the other many challenges that this project means for me. It is nice to know that my mig is capable of welding 6mm ally. However after what I have been through to make the concrete base for this ramp, augering 2.7m down, building the cage, sourcing the sleeves, hiring the excavator and operating it on my own, pouring the concrete, drilling the 26mm holes for the 24mm studs, gluing the studs with epoxy, cutting the PFC, drilling it not to mention swinging them around at 50 k each, I want to take a mental rest and deal with a material i am confident with

Weight. One piece construction will always be lighter than sectioned construction. Your heaviest component will be the timber decking. Could be worth looking at expanded metal decking, particularly if you go all aluminium construction.
The lighter the structure for a given strength, the easier the installation and the more it can carry.
Also see earlier comments re. ballast and buoyancy, I guarantee that some adjusting will be required.

Yes, the wood is heavy, 80 k more if hardwood instead of treated weed, however if I use TP because I want to reduce the ballast by 40k, I will kick myself for the next 10 years each time I look at the TP sucking up the rain. Mesh is good but I will need an additional central support and that will minimise any weight advantage not to mention cost.

Strength. Is this pontoon installed in a tidal river? YES Do you have floods? YES What about debris like trees etc being carried by the current and impacting your pontoon? Only minimal rubbish like reeds or canes.
At least put some diagonal bracing in the floor, but possibly consider a couple of guy lines. Load bearing strength is easy to achieve with the massive truss that the side rails provide. If you allow for 2 80Kg people per square meter then you will be on the safe side of life.

The ramp will have two diagonals say 50x50x5 angle, bolted to 2 short flat bar on each inside of the bearers. Perhaps need to be in two sections so two X each 2 meters long to make it more effective, all under the hardwood decking material. Considering that the "deck" is 6x2 hardwood bolted to a flat bar, The diagonal is hardly necessary since each piece of hardwood if bolted properly should keep the thing fairley square, yet for a few dollars more I can make the diagonals as well. The pontoon has two extra anchoring points at each end, for two stay cables that cross under the ramp and attach to each end of the 2.2m 30mm Stainless Steel bar that acts as pivot for the ramp. A 100x10 mm flat bar bent at 45 degree, welded to a hollow bar 50/35 slides at each end of the bar and acts as the fix point for the 12mm SS stay cable. I also sourced a stainless steel tensioner to adjust the pontoon position and compensate for cable stretch if that even happens with that sort of loads.

Overall, if it were me and other factors allowed, I would build a one piece, Aluminium structure out of box section and deck it with heavy expanded aluminium mesh or aluminium walkway mesh.
Apologies for the lengthy post.
You are very welcome. I wish we were neighbours and could build this together in aluminium. As it stands it will have to be RHS steel. I'll get onto the OneSteel engineer and get the load capacity of a 4m piece of 150x5x3 and also for 100x50x3 and take it from there. From what I have seen built, it seems that 100x50 is plenty.
I'll keep you posted and thank you for your valuable input as usual.
Hooroo
Marc

I've always found that 2 off 12mm holes in each end were more than adequate for ventilation and drainage when galvanising, usually placed diagonally at opposite corners of the capping plate.
It sounds like you have your bases covered and have thought out the job.
A good etch prime and two pack epoxy will really beef up the corrosion resistance of your pontoon and that water isn't too bad anyway.
Actually paint sometimes stands up better than anything. The underground mining vehicles I used to build were sprayed underneath with black enamel until it literally dripped off the underside, it was the only thing that protected them from the mud and water.
When you weld up your sections, make sure to wire brush/chip all the silicon off the welds. The pickling bath won't remove it and the galvanising won't stick to it either. The same applies to slag from stick welds.

OK, finally got my answer from a structural engineer, the very same that has my plans and never bothered working on them. So out of guilt I probably got my answer ha ha. So it turns out that an RHS 150x50x3 spanning 4 meters will hold 100 kilos per meter that is 400k if spread evenly or 300 if the load is in the centre. Since I have 2 of them, it is twice as much so that means that with two RHS of that size I can make the ramp with no handrail and it will have way over the strength I need holding 600 kilos in the centre.

[QUOTE=Marc;1832390]Karl Robbers;



Weight. One piece construction will always be lighter than sectioned construction. Your heaviest component will be the timber decking. Could be worth looking at expanded metal decking, particularly if you go all aluminium construction.
The lighter the structure for a given strength, the easier the installation and the more it can carry.
Also see earlier comments re. ballast and buoyancy, I guarantee that some adjusting will be required.

Yes, the wood is heavy, 80 k more if hardwood instead of treated weed, however if I use TP because I want to reduce the ballast by 40k, I will kick myself for the next 10 years each time I look at the TP sucking up the rain. Mesh is good but I will need an additional central support and that will minimise any weight advantage not to mention cost.


You might like to explore the composite decking which is now being used in some of the Nature Reserves for elevated board-walk decking. Sorry I don't know the trade name, but it is a high strength grid pattern with a non-slip surface and comes in modular form, 1sq Metre I think. I suspect it would be lighter than TP. No idea of the cost.

Another option for the structural members might be the range of Zed and Cee Purlins used in industrial roof construction. They are supplied hot-dipped galvanised, and load tables are available on-line . Google is your friend.

Chas.

Originally Posted by Marc

OK, finally got my answer from a structural engineer, the very same that has my plans and never bothered working on them. So out of guilt I probably got my answer ha ha. So it turns out that an RHS 150x50x3 spanning 4 meters will hold 100 kilos per meter that is 400k if spread evenly or 300 if the load is in the centre. Since I have 2 of them, it is twice as much so that means that with two RHS of that size I can make the ramp with no handrail and it will have way over the strength I need holding 600 kilos in the centre.

There would be a BIG safety margin at those loadings. Many a 3-4 tonne tip tray has had less holding it.
Would you really want a ramp without a handrail? I think your insurance company may have other ideas. Leaving legalities aside, a handrail makes the ramp look complete and is a safety feature particularly if you are carrying anything on the ramp or there are children involved.

Yes, it is true that a handrail has its advantages particularly at low tide when the ramp becomes rather steep. I guess that in my excitement of finally having data that has eluded me for a while, I realize I don't need to have a handrail as part of the structure and can therefore add it after. As far as mesh, I looked into it at Edcon Steel, they sell all sort of structural mesh for industrial catwalks and the likes but besides being horribly expensive, it weights a ton and a half. Unless I use aluminium mesh at even higher prices, there is no weight advantage at all. For the lighter material and for the aluminium mesh, the need for a third beam negates all advantage. I'll make some more enquiries, the mesh is an attractive alternative as opposed to 150 kilos of hardwood but at 30 kilos per m2 I have 120 kilos right there, and that is with a gage that does not span more than 500 so need a middle beam.

http://www.tiloncomposites.com/page24.html . . . . . Is this the one you refer to? I wonder if there is a local supplier?

Originally Posted by Marc

http://www.tiloncomposites.com/page24.html . . . . . Is this the one you refer to? I wonder if there is a local supplier?

It looks like the duck's gut's. Perfect for your needs.

Dean