rule of thumb for boat slip size

[Easternshore]

Just did a search (internet, trawler forum, etc.) on a rule of thumb for calculating the optimal size slip and came up with nothing. While there are many variables such as the boat's draft, beam, LOA, tide conditions etc. no "rule of thumb" could be found.

Question is:
our LOA is 36' 1", beam 12' 3", draft 3' 6", tidal change is 1', a protected marina. We are in a 40' X 15' slip 4'6" MLW which to me seems perfect.

The admiral found a 50' x 16' she likes, 4' 5" MLW but the pilings are at the dock, mid slip (25' out) and the end (50' out.) I think it is too long for our boat and would appreciate any thoughts. I think a 45' length would be a stretch (no pun intended) but 50' seems too long.

 

[rslifkin]

There's no real rule on this one. And different marinas will have their slips proportioned differently (as far as length vs width, cleat and piling placement, shape of docks, etc.). So in my mind, it's just a matter of seeing what's available that the boat will fit in, and then picking the one you like best or that's easiest to get the boat in/out of.

To me, both of those slips are way too shallow. Given a choice, I like 3+ feet under the boat in the slip. Ideally 4 feet, as that's about what it takes to minimize stirring up mud while maneuvering in and out with my boat.

 

[psneeld]

Floating or fixed?

Finger piers and how long?

Without a picture or diagram with piling and cleat positions hard to tell,, especially floating or not.

Sounds like no need with a q foot tidal range, but ya never know for sure.

You can certainly tie up in a larger slip, just may be a bit more of a PIA, but just a little if done with a little ingenuity.

Big slips in storms can be a blessing

 

[Easternshore]

Thanks

Good points, thank you, the new dock is floating with 15' finger pier on one side, wanted to keep it easy for her to tie the bow. Cleats are at bow, stern and midship, swim platform and bow pulpit add the total length to 40'. I was concerned about too much line at the bow as we like to keep the swim platform 2-3' from the dock.

 

[Easternshore]

I agree about the depth, easy to kick up mud at low tide.

 

[firehoser75]

To me, there really isn't a "rule of thumb", it is much more dependent on personal "wants".

Having more depth (certainly more than 1 "extra" foot (compared to draft) at low water) is a good thing. I would not be happy with the depth you describe, but that may be "area dependent" and choices could be limited.
Ease of docking and leaving are important to me. If it is always an "adventure" then that is not the slip for me. I don't need the stress. We have had slips where you only had enough "extra" beam width to barely fit (squeeze) a fender between the boat next door and ours and another one between our boat and the dock (on the opposite side). Too tight when facing a cross current and/or cross wind, especially if it is just you and another person on board (or worse - solo) and sometimes (due to the lack of space) the fenders will "run up" and not provide the "cushion" you are hoping for to stop scrapes, etc. Also, having a bit of "extra beam space" to accommodate line stretch during a storm (and to allow placement of extra "oversize" fenders) is not a bad thing in my opinion. Sometimes the longer slips are located where the fairways are also a bit wider (in comparison) often allowing for easier manoeuvring, but generally you also pay by the foot for either overall boat length or slip size so they can cost more. Otherwise, slip length is not that much of a factor to me.
As stated by others, the other factors to consider are piling placement; cleat availability, placement, and number; and location of water bib and electrical connections (sometimes they are poorly placed and/or arranged).
I suggest that you have to look at all of these factors (having ranked the factors for importance to you), and then make your determination based on each specific slip as to what "works best" for you out of what is available. Right now, around here, you would be lucky to find a slip, so choices are slim.
Good luck and hope you find some helpful info in these posts.

 

[psneeld]

What I have seen and would recommend......

IF AND ONLY IF...... the marina is truly protected. Even that isn't hard and fast if you have a good eye for tying up boats.

Take a small boat out and tie a line from each outer piling to the midship pilings.

Splice, or have someone splice your now short and tight bow lines to an appropriate point in those 2 lines you tied to the pilings.

Untie to get underway, hang the bow lines over the others, grab with a boat hook when returning.

 

[tiltrider1]

I think I’m at the opposite end of the country from Easternshore. I never worry about depth in our marinas even with our 16’ tide swings. I worry about how wide the slip is. How wide the fairway is and how wide the finger pier is. I might pass on a marina if the ramp is too steep at low tide.

 

[Bacchus]

Just my opinion...
Many (mostly inexperienced) boaters figure the larger a slip is the easier in & out. I disagree and recommend to folks to think about how they will detach & hang lines when leaving and how they will grab and reattach when returning. Will you always have agile & experienced cew or single hand at times.
A properly sized slip is easier to handle than one that is too long or wide.
One obviously has to also consider prevailing winds / protection and currents. Best to try out a candidate but if not possible at least draw some to scale layouts of slip & boat and work through the maneuvers.

 

[DDW]

On depth, do you have a diver clean the bottom? If so he will not like it being that shallow.

 

[rgano]

The depths you mention are only one inch different; so there is essential no difference. The draft you mention is surely the lower tips of the props. A little bit of judicious "engine testing" in the slip would likely change that a bit.

On the rare occasion we moor in a marina slip I want the boat tied off at all four corners to prevent the soft Awlcraft paint from getting buffed by fenders et al. Been there, done that ($2,000 bucks to fix). It is a tremendous PITA to deal with a big boat slip as we fumble about finding lines long enough to do the trick while pushing and pulling the boat about to attach them. I suppose in a permanent slip you will have permanent lines set up, but if you have a setup where there is a finger pier every other boat, you are going to be stuck with having to fender your nice red Awlcraft against some part of a pier.

 

[FF]

For a liveaboard the slip furthest out will catch the slight breezes ,have the best view, and have the least foot traffic.

 

[rwidman]

If you travel to different places on your boat, you will soon learn about slip arrangements and tying up your boat.

Where I live, marinas all have floating docks because of the tidal swings and most have full length finger piers. Docking is simple, tie your boat to the cleats on the dock and the finger pier.

If you're in a situation where you have to tie the bow to pilings, things quickly get difficult if the pilings are further out from the dock than the bow of your boat. This happens when the slip is too big for your boat (and we have a relatively small boat so this happens to us fairly often). Ideally, you would be able to reach the front pilings from the bow of your boat.

 

[rwidman]

For a liveaboard the slip furthest out will catch the slight breezes ,have the best view, and have the least foot traffic.

True, but it will be the most subject to wakes, waves and storms. And it will be the longest walk to the parking lot or heads.

You pays your money and you takes your choice.

 

[OldDan1943]

I agree about the depth, easy to kick up mud at low tide.

Or dock bow in so folks cant look in to see what you are wearing nor not wearing.

 

[rslifkin]

Or dock bow in so folks cant look in to see what you are wearing nor not wearing.

That's always an option, although depending on their layout, some slips lend themselves to one direction vs the other.

In my current home slip, we back in, as there are pilings at the outer end on both sides. The way everything is placed, it just makes more sense to put the skinny end of the boat out there. Plus, the finger pier is tapered at the outer end, so it's easier to get on/off when backed in.

If we moved across the fairway, the docks there have angled corner pieces at the inner end of the finger pier and no tapered fingers, so I'd probably go bow in, as we'd fit about 4 feet further into the slip that way.

 

[Gdavid]

For a liveaboard the slip furthest out will catch the slight breezes ,have the best view, and have the least foot traffic.

Says man with large bladder, large holding tank or both

 

[rslifkin]

Says man with large bladder, large holding tank or both

Or docked in an area with a pumpout boat service (better yet, a free one) where getting the holding tank pumped frequently is no big deal.

 

[Gdavid]

Or docked in an area with a pumpout boat service (better yet, a free one) where getting the holding tank pumped frequently is no big deal.

D'oh, you just reminded me that I forgot to submit my pump out request, they are due each Sunday night.

 

[PPandE]

Go with the one the wife likes and make it work. Occasionally mention what a great choice she made.

 

[Gdavid]

Go with the one the wife likes and make it work. Occasionally mention what a great choice she made.

Pure genius, well done sir.

 

[soin2la]

Go with the one the wife likes and make it work. Occasionally mention what a great choice she made.

Absolutely, then you are covered when her next idea comes up; a bigger boat.

 

[PPandE]

I know nothing I haven’t learned right here.

 

[sbu22]

Or dock bow in so folks cant look in to see what you are wearing nor not wearing.

Indeed. Plus easier in and out.

 

[Hippocampus]

Only thing I truly dislike are those very short fingers of 4-6’. You need to Med moor bow out. They’re especially bad when there’s only one per boat so if your neighbor hasn’t done theirs correctly his boat can pivot on the middle piling and strike yours. Even worse is when there’s no fingers at all and no pilings. Just straight Med moor. Haven’t fingered out a way to moor or leave by myself from a Med moor except in dead calm with no current.
I like a finger on each side of the boat. Some days it’s better to come in bow first. Many boats are more controllable bow first when you’re moving at extremely slow speeds. Think ideally your pier should match your LOA as close as possible. Pilings should be inside the footprint of the finger. Floating is easier on you and the boat. Passerells and dock steps shouldn’t be necessary.

 

[rslifkin]

Only thing I truly dislike are those very short fingers of 4-6’. You need to Med moor bow out. They’re especially bad when there’s only one per boat so if your neighbor hasn’t done theirs correctly his boat can pivot on the middle piling and strike yours. Even worse is when there’s no fingers at all and no pilings. Just straight Med moor. Haven’t fingered out a way to moor or leave by myself from a Med moor except in dead calm with no current.
I like a finger on each side of the boat. Some days it’s better to come in bow first. Many boats are more controllable bow first when you’re moving at extremely slow speeds. Think ideally your pier should match your LOA as close as possible. Pilings should be inside the footprint of the finger. Floating is easier on you and the boat. Passerells and dock steps shouldn’t be necessary.

Agreed. The only time a short slip isn't a pain is when backing in, and even then, only if it's not more than a few feet shorter than the boat. Steps on the dock are sometimes needed with lower floating docks and tall boats, but we've solved that with a small folding step ladder that stores neatly in a closet and is easy to place on the dock (light weight).

 

[MVDarlin]

Marinas charge by the foot. If they tell me I can moor my 52 ft overall trawler in a 45 ft slip and have 7 ft in the fairway I say sir, yes sir as long as they charge me for 45 ft.

 

[Bacchus]

Marinas charge by the foot. If they tell me I can moor my 52 ft overall trawler in a 45 ft slip and have 7 ft in the fairway I say sir, yes sir as long as they charge me for 45 ft.

Many charge by the foot but some charge for a slip and spec a max size you can put in it.
We pay a flat fee for the slip we chose. We have a 34 but it will take up to a 50. We prefer the location and we are 14 beam which is too tight in other slips for up to 36.
The marina doesn't care what we put in the slip as long as it doesn't exceed 50ft.

 

[chefH2Os]

Great Idea

What I have seen and would recommend......

IF AND ONLY IF...... the marina is truly protected. Even that isn't hard and fast if you have a good eye for tying up boats.

Take a small boat out and tie a line from each outer piling to the midship pilings.

Splice, or have someone splice your now short and tight bow lines to an appropriate point in those 2 lines you tied to the pilings.

Untie to get underway, hang the bow lines over the others, grab with a boat hook when returning.

I think this is a great idea! You’re suggesting that he splice in spring/breast lines into a drunk line, right? For long term moorage, piling placement becomes a nonissue. Fantastic.

 

[markpierce]

I'm OK with an over-sized berth. My choice.