Concrete boat ramp extension

Heres a bit of a diff question...I have a concrete boat ramp that is only usable when the water levels are high (not lately!)and wanted to add to it. It only reaches the waters edge right now and I need about 5 ft more to sink the trailer. Any engineering gurus know of a concrete that will cure underwater?

Your best bet would be to construct a frame out of 2x4's and put poly underneath and pour yourself a slab. You would need a tractor with a bucket, but you could then slide the slab past your current ramp. This should give you the extension you need. Just be sure to let the concrete cure for 96 hours.

I believe Portland Cement is thee type that cures under water.

Most people just dam up the area that they want to work in, drain the water and have at it. Sandbags should work just fine.

Troys right, set up a coffer dam and pump the water out. Then pour your concrete.

J, all these guys are right, but if you want to go a low-tech route, you can place bags of regular sak-crete where you need them and they will cure underwater. Just leave it in the bag; the water seeps in and it cures in place.

Make two rows the same width as the trailer wheels, and bury them down in the sand as much as possible. Ideally, the tops of the bags would be even with the natural lake bottom. To keep the bags from shifting, drive pieces of rebar thru the bag into the lake bottom, making sure the top of the rebar is recessed a little.

A guy at my office did it by placing #67 stone to extend the ramp. Then, he got these metal mats that the military used to park airplanes on and placed it on top of the stone. It worked great.

Try a concrete mat that you could just drag down and leave it down in the water (if you want to go the expensive/hi-tech way). Get the open cell mats so you can fill in the openings with rocks. The concrete blocks will also provide lots of traction.

http://www.armortec.com/
http://www.hydrotex.com/index.htm
http://www.shoretec.com/


Since yours is not a heavily used ramp, I'd go with the low-tech way, get the building blocks (open cells) at Home Depot/Lowe's/etc. and lay them down one by one, fill in the cells with crushed rocks for anchoring, weight, and traction. Easy to do, just time consuming and labor intensive.

Coffer dam is a great idea but you need the right equipment to do the job safely and you also get into OSHA requirements, etc. too costly for this little job.

Regular sac-crete is ok at first but over time, sediments and vegetation will build up and grow on the outside and it will be very slippery. Not to mention, when it cracks, the re-bars (if you use them to anchor the bags) will be a hazard and can damage your boat or injure someone walking on the ramp.

Great input from all. Kvoman, the links are great. When you refer to the building blocks (open cells) at Home Depot which ones are you referring to? Do you know how they refer to them or what the normal application is? Tks

I have another suggestion...

I acquired (no I didn't steal them) two aluminum ramps used in Uhual moving trucks... They are 12 feet long and 30+ inches wide... I laid them at the end of our ramp where the trailer tires would go and used stakes to hold them in place... But once they sank into the lake bottom they never moved...

This was a fairly easy way to extend our ramp another 12 feet.

These blocks are the kind that is used to build retaining walls, they are usually on pallets in the garden area. Some are closed cell (one big chunk of concrete block w/o the hole(s) in the middle), some are open cell - these are the ones with the hole(s) in the middle so you can place crushed rocks in there. You can buy these as individual pieces or as a pallet.