When determining the correct model of Aqua-Stairs® swim ladder, you need enough stair steps underwater to comfortably get onto the ladder. This means that for most people and pets, you want to have the bottom step a minimum of 2’ below the water. From experience, it is best to be at least 2’4” below the water. This is because the deeper the steps are into the water, the easier it is to use the swim steps. The way to determine the correct ladder for your installation depends mostly on the distance from the mounting surface (top of the dock) to the waterline (surface of the water). The other consideration is how deep the water is; more on that below.
Floating Docks are always the same distance "A" above the water - see diagram below. Make sure the last step on your Dock Ladder is no longer than distance “B”. Otherwise, the ladder might get stuck in the dirt. Of course, with seasonal lowering of the water, you can rotate the dock stairs out of the water when the water goes down since all Dock Ladders ship with flip-out brackets.
With fixed docks or piers (see diagram below), you will need to ensure that the ladder is long enough at lower water levels to accommodate the distance “Y. Keep this in mind if your water levels fluctuate during the season when you use the dock stairs.
This comes into play with tidal changes or seasonal water loss. This may not be a concern if your water levels do not fluctuate during the season. Also, Aqua-Stairs ladders do not need to rest on the bottom for support when mounted correctly. Many customers size their Dock Ladders to step up from the sand onto the bottom step at low water levels. Others just let the ladder rest on the sand or bottom. If you are in very deep water, this is not a factor. Keep in mind that the ladder might ‘stick’ to the bottom if sunken into the muck.
In consideration of the above and as long as your installation water depth is sufficient, we recommend the ladders as follows:
A 3-step Dock Ladder is best used when the distance “A” or “Y” is 12” or less. If the distance is more than 12”, you will need a longer ladder unless distance “B” or “Z” is 3’ or less (it would be stuck in the dirt).
A 4-step Dock Ladder is best used when the distance “A” or “Y” is 24” or less. If the distance is more than 24”, you will need a longer dock ladder unless distance “B” or “Z” is 4’ or less (it would be stuck in the sand). The sweet spot for a 4-step model is when the distance is 12-20”. While it can be used up to 24”, it is far more comfortable to go the 5-step ladder as you approach the 24” distance above the water.
A 5-step Dock Ladder (or the Special 7 step ladder) is best used when the distance “A” or “Y” is 36” or less. If the distance is more than 36”, you will need a longer dock ladder unless distance “B” or “Z” is 5’ or less (it would be stuck in the muck). The sweet spot for a 5-step model (or special 7 step) is when the distance is 21-32”. While it can be used up to 36”, it is far more comfortable to go the 6-step ladder (or the Special 8 step ladder) as you approach the 36” distance above the water.
A 6-step Dock Ladder (or the Special 8 step swim ladder) is best used when the distance “A” or “Y” is 48” or less. If over 48”, you will need a longer Dock Ladder unless distance “B” or “Z” is 6’ or less or if close enough to the bottom to step onto the last step. The 6-step and Special 8-step ladders are the longest in our product line.