Understanding Tides For Launching/Docking

[ralphsmithiii]

Hello everyone!

There's something I'm not 100% sure about and wanted to see if I could get some feedback on. I may be way over thinking this but I'm looking to get some info regarding this example tide chart:

With tides you have two highs and two lows. For this post, I'd like to skip the science behind it. What I'm interested in knowing is, how does the low and high tide in this chart correspond to launching/docking a boat? For example, you can see its -0.7ft at 8:16am. Meaning, if zero is the assumed starting point then -0.7 would be, well seeing some sand at the shoreline, correct? At 2:37pm we see a high tide of 2.5ft meaning the water is 2.5ft above 0.

So, if you wanted to hit the ramp at 10am and launch your boat, this chart would assume a 0.2ft height of tide and slowly rising until 2:37pm. How does .2ft correlate to the actual depth of the water at the docks? My broken (at the moment mind) is saying...the water is only .2ft above sea level? That causes me to pause and think, that's not right I'm really missing something here. If I look at random charts from previous days/month/etc at the same location this chart isn't too far off the average and yet I know people launch all kinds of boats from this dock around the 8-10am time frame.

What am I mis-interperting so I can better understand when its idea to launch on any given day at any giving dock.

 

[mdchachi]

The starting point is not zero, it's the average low-tide mark. If there's still enough depth for your boat even at low tide then you are fine and can launch then.

 

[swatski]

Once you know what "zero" looks like at your favorite ramp, you will be able to figure out the levels that frame your comfort zone/range and then look up the charts for launching feasibility.

--

 

[Julian]

Good ramps are long enough and go deep enough that tides don't matter at launching.

What I'm no good at is how to tie a boat up well at a non-floating dock with tides....I know the theory, but practice makes perfect. Especially in a slip with pilings on both sides. If it gets too narrow, then in the 2nd image you can see that the boat has to have enough slack to allow it to float out sideways....but not so much that it will hit the piling on the other side. This is why I like floating docks!

If at all possible, try not to 'short tie' your boat. By that I mean that the lines should be long enough that when you have extremes of high or low tide, your boat will be able to ride up and down without stressing the line by hanging on it or pulling on it.

 

[Cambo]

That type of tide chart is confusing

look for your location on this site

https://www.weatherforyou.com/reports/index.php?forecast=tides&place=flanders&state=ny&zipcode=

On long island we have the north shore , south shore and from one end to the other the tides are dramatically different and I like launching in different areas this tide chart makes it very simple to see high and low tides.

This chart shows the high and low tides for the day and total height so at low tide if I see a sand bar exposed I know at high tide I can safely pass over it .

 

[haknslash]

Good ramps are long enough and go deep enough that tides don't matter at launching.

I don't know, maybe that's how it is where you live but that doesn't seem to be the case where I've launched in FL. For instance in Panama City Beach, the bay and surrounding lagoons are relatively shallow throughout except in the channels. The depth can get shallow VERY quick without notice and they move because of shifting sands. The launch I use in Grand Lagoon I think the average depth is a 3-4' pretty much all across the water. When you launch the low depth alarm will be blaring off and on until you get out into larger waters lol. Knowing when the tides change I would say is an important thing to understand and don't just assume because there is a launch or long pier that is means it's deep and you're good to go throughout the day. Really depends on where you're boating IMO so understanding those areas is vital to keeping your hull off the bottom.

This pic it looks deeper than it is because of the dark water color but trust me it's super shallow in this area and I've almost ran my boat aground by the overpass because I wasn't paying attention to channel markers lol. Even with the dark waters you can see those really shallow areas that are the 1' to 2' depth range IIRC.

 

[Beachbummer]

The proper tying technique is critical. We had an old glastron 19ft sink when tide was unusually low and the boat went under the dock, then the rising tide flooded it.

It was an outboard and the engine was never submerged, so there was no lasting impact, but we learned that one by experience. It was a bear to get the boat dry that morning... Took us a couple of hours of bailing.

 

[swatski]

Good ramps are long enough and go deep enough that tides don't matter at launching.

What I'm no good at is how to tie a boat up well at a non-floating dock with tides....I know the theory, but practice makes perfect. Especially in a slip with pilings on both sides. If it gets too narrow, then in the 2nd image you can see that the boat has to have enough slack to allow it to float out sideways....but not so much that it will hit the piling on the other side. This is why I like floating docks!

If at all possible, try not to 'short tie' your boat. By that I mean that the lines should be long enough that when you have extremes of high or low tide, your boat will be able to ride up and down without stressing the line by hanging on it or pulling on it.

The proper tying technique is critical. We had an old glastron 19ft sink when tide was unusually low and the boat went under the dock, then the rising tide flooded it.

It was an outboard and the engine was never submerged, so there was no lasting impact, but we learned that one by experience. It was a bear to get the boat dry that morning... Took us a couple of hours of bailing.

Sure... But the OP question was not about mooring...

What am I mis-interperting so I can better understand when its idea to launch on any given day at any giving dock.

The simple solution, and really the only solution, is to know your gauge and your ramp. Once you know the levels at the particular ramp and its surroundings at any given tide (or water level in general) - you will be able to make a decision what is safe.

Many if not most ramps are not linear in slope.
Tide level predictions are exactly that: predictions.

My advice would be:
1. know your ramp and the surroundings, follow the locals if in doubt or in a new place
2. read the gauge and go boating, or not

--

 

[Julian]

But the OP question was not about mooring...

OK....I translated "docking" in the title to "Mooring"....

Know your ramp is the best advice. And if you are going somewhere new....we probably have someone on the forum thats used that ramp before, so don't be afraid to ask.

 

[Bluewater272]

You're understanding the basics of the tides' impact on launching, but it really takes local knowledge of the ramp. There are two ramps that I often use, one I can use at dead low tide without an issue. The other one I have about a 1' margin for backing to an accurate depth before the trailer falls off the ramp into the mud - prime opportunity to become a youtube star. I don't use the latter anytime near low tide, and if I get back at low, I tie up and wait a while. Not worth the risk.

That causes me to pause and think, that's not right I'm really missing something here. If I look at random charts from previous days/month/etc at the same location this chart isn't too far off the average and yet I know people launch all kinds of boats from this dock around the 8-10am time frame.

Tides shift by about an hour a day. 8-10AM will not always be low tide.

 

[Cobra Jet Steering LLC]

Every location is different, The tide is good to know but the average depth at certain tides is more important , so on a low number you need to remember how that worked out at the water so next time you see that number you know what to expect.
Wind has an effect on the tides also, so one day a -1 low tide is no problem when another day it may run shallower.
I have fixed objects near where I launch and I can use those as an indicator as to how safe it is to run out of the channels. You need to compare the tide levels when you use the boat and after a while you will have a good understanding of what the numbers mean to your location. I also hate those tide charts and I print out the tides 2 weeks at a time for my boating location I hang that chart on the wall and reference it each time I go out but I beach launch so it is vital to know what the tides are SUPPOSED TO DO ! Not that they always do it. I hate returning to find my van sitting in 12 inches of salt water because the tide ran higher than I was expecting .

 

[BigAbe75]

It sounds like such a hassle to live on the coast!

If I go out for a weekend, my water stays the same level for the duration of my stay. So much less confusing.

I mean, sure... you can boat year round, have awesome beaches and all that. But who really wants to boat all the time, anyway. lol

 

[Gym]

With regard to tides, chart depths and bridge heights from the water they are based on "mean low tide".
With regard to tiring up to a fixed dock where you're not familiar with the tidal delta you can use your standard dock lines fore and aft (leave a lot of slack on both. Then you can use the stretchable dock lines. Such as the Dock Snubber.
https://www.overtons.com/product/de...3wBlZQaIG5l7fSomenenoMJZ_8VHA2rhoCO2cQAvD_BwE

It would most likely be a problem if you tied up at dead low or high tide and remained for 12 hours. Most locals can tell you what the tidal change is. Where I am its 18" but can change during a storm, full moon or a lot of wind following the tidal direction.

Sorry for any misspellings. I'm in the hot tub and my glasses keep steaming up.