Owning a boat sucks!

[Hermit Scott]

That is a pic of my boat on a private dock where I bought it. The po tied it up like that. That is some very calm water and no tide to speak of. After this thread, I am wiling to pay extra for floating docks. It seems very convienent.
Cpt. Jon it is possible I thought I left plenty of slack but the lines were not crossed across the stern like recommended here. That is definitely a possibility for being part of this problem.
It doesn't look like I will get down to reapir that until Friday. I haven't done anything to my boat since I got to this marina becasue there is no power on the slip I am in. I have to move closer to the shore to get power and water.

 

[Ron20324]

My slip neighbor has a C30, and his swim ladder causes some problems with crossing the lines. Also, be careful of where you tie to the pilings. The lines should be about horizontal to the boat at mid-tide position. I see many lines tied so high on the pilings that the boat actually hangs on the lines at low tide- very easy to lift a cleat out of the deck that way.

 

[jibes138]

Please explain SD

BTW, quadrupling the lines up like you have on the bow are a likely reason for the damage to your boat. If the lines are that heavily setup, they can't stretch much and the loads on the cleat are higher on the cleats by at least an order of magnitude.

I can understand the impulse imparted to the boat by sudden shock loading, but if you look at it as a statics problem a force is applied to the boat that is resisted by the line. Once the boat reaches the maximum stretch of the line (modeled as a spring) for the given load it is a straight statics problem and the force on the cleat is independent of the number of lines attached. No question more loops of line will stretch less but the final force on the boat will be identical once equilibrium is reached. Perhaps the rapid deceleration caused by more strands of line is what is being considered. In this case say the lines are slack and a strong gust sets the boat in motion taking up the slack, then stretching the line until it reaches equilibrium with no motion. In this case F=mA will apply and since the acceleration (in terms of deceleration) will have a large magnitude and thus the force generated will be higher. So shock loading will be greater but static loading should not be. Can you expand on your comment please?
Thanks
Dave

 

[catsailor]

It is not a statics problem. It is all dynamic.

I can understand the impulse imparted to the boat by sudden shock loading, but if you look at it as a statics problem a force is applied to the boat that is resisted by the line. Once the boat reaches the maximum stretch of the line (modeled as a spring) for the given load it is a straight statics problem and the force on the cleat is independent of the number of lines attached. No question more loops of line will stretch less but the final force on the boat will be identical once equilibrium is reached. Perhaps the rapid deceleration caused by more strands of line is what is being considered. In this case say the lines are slack and a strong gust sets the boat in motion taking up the slack, then stretching the line until it reaches equilibrium with no motion. In this case F=mA will apply and since the acceleration (in terms of deceleration) will have a large magnitude and thus the force generated will be higher. So shock loading will be greater but static loading should not be. Can you expand on your comment please?
Thanks
Dave

There are a number of factors that effect the impact:
* how heavy the mass.
* how long it has had to get going (spring lines can reduce this a lot)
* how long it has to stop.

With a steel cable, the force can aproach infinity, or certainly VERY high values, for just a moment. On the other hand, if I gave you one end of a 50" fishing line and told you to pull and break it, I bet you could not, at least not without a big running start.

Another way to look at it is that a hammer can only impart 12oz. of pressure in equilibrium. Striking and anvil might take that to 25,000 pounds or so.

Curiously, though climbing gear is rated for strength, rock climbing ropes are actually rated for their ability to absorb energy. That is far more important than their strength. A rope has to stand a certain number of specified impacts AND not exceed a certain maximum force in the process. Too strong a rope will fail!

 

[CarlN]

The others are quite right - you want stretch. This will take the shock loading off of the cleats. Regular three strand nylon is fine. Yale makes an especially good braided line called Brait (8 strand braided) that is designed to be especially good at absorbing shock loads. Rig the springs but also lead a line forward from the bow and back from the stern. Try not to have any really short lines.

At least in the picture of the PO' dock - those fenders aren't big enough either - especially on a fixed dock. You want some "now-that's-a-fender" fenders. Maybe 8" or 9" x 30" - and four of them. The length will keep them from jumping out. They'll be a bit of a pain to stow but it's better than damage.

Also, watch for any places that the dock lines might chafe and put on some chafe guard. Clear vinyl water tube from Home Depot works fine. Poke a hole in each end and tie some cord through it to keep it from sliding along the dock line.

Carl

 

[sailingdog]

The shock loading is a matter of the rate of deceleration or acceleration, rather than total force. If you have four lines like that the g-forces are much higher and the chances of the gear breaking is much higher than if you only had one line. The problem is exacerbated by the fact that the line is tied in such a short length and that the four lines are frapped together by wraps around them, so that they can not move or stretch independently to any real degree. Also, frapping the lines like that pre-loads them with more tension by removing any slack that might normally be there.

You'd be surprised at how little movement is required to generate high g-force loading. dropping into a chair from a standing position can generate about 10 g-forces. A boat moving the same distance, ie less than two feet, due to storm surge can also probably generate 10 g's of force.

I'd also point out that normally, tieing the docklines bar tight like that is a really bad idea. Some slack is a good idea... If you're going to do multiple dock lines for storm or heavy weather situation, the secondary lines should be slightly more slack than the primaries, so that they can take over if the primary lines fail. If they're as tight as the primary lines, chances are good that both will fail simultaneously.

Also, the fenders in the photo are quite small for a 30' boat. I use 8.5" diameter fenders and more of them than shown in that photo for a boat that is considerably lighter than that boat is.

One last point I'd make is that the two most common modes of failure for dock lines, anchor lines and mooring lines are chafe and failure due to internal friction. If you use plastic hose as the chafe protection, you're far more likely to suffer failure due to internal friction, since the water can not get into the line to cool and lubricate it, and the chances that the friction of the line working will get high enough to generate enough heat to cause the line to fail goes up greatly, since the hose also acts to prevent the heat from escaping. Using woven polyester/spectra chafe sleeves or webbing instead of hose makes much more sense, and is generally what I recommend.

 

[jibes138]

Acceleration and Deceleration - SD more help needed

The time rate of change of acceleration is also know as the "JERK" :>) I am not making this up.
So let's assume the dock lines are cinched up so tight that the boat can't move, as if there were steel cables holding it in place. In this case there is no acceleration or deceleration due to the lines being slack then reaching their maximum spring elongation for the given load. In this case the force on the cleats would be related to the wave and wind force on the boat itself. So the question is are the cleats strong enough to overcome the bouyant force of the boat and force the boat deeper into the water or in the case of a wave trough are they strong enough to hoist the boat out of the water. It seems like cleat design should be such that the screws would act like shear pins and fail before the cleat ripped completely out of the deck? The other interesting phenomena is the way the stern cleats are oriented on the Catalina 30. The lines are such that they are trying to load the cleat from the side versus pulling on the length of the cleat so there is a greater bending moment on the screws versus just a shear force on the screws. The bending moment puts a large vertical force component on the washers and nuts under the deck trying to rip them out versus trying the pull the srews through the material horizontally or shearing the steel screws at deck level. Any thoughts on these comments?

 

[luvitt]

if you have to tie up to fixed pilings you could get some of those floating donuts that go around the piling and float with the tide. We dont have fixed piers anywhere in Charleston that i know of, so i am lucky. but i had fixed piers in MD and it was a pain until i got those donuts. i went through hurricane isabel onboard and the storm surge was so high that i would have been pulled under unless i was there to move the lines. that was an experience! i had to swim to shore the next day, through all kinds of nasty stuff. i didnt have the donuts then.

 

[sailingdog]

Well. Yes, cleats are supposed to be loaded along their longitudinal axis, not perpendicular to them, since the lines are generally meant to be led to the cleats at a fairly acute angle.

That is a big part of why the docklines may have torn the cleats from the boat—since the way the boat is tied up, the lines are loading the cleats primarily perpendicular to the cleat, rather than along their access, and the height of the cleat is acting as a lever arm against the bolts—creating a bending moment rather than pulling in shear against them as you said.

If you look at this diagram of docklines, the lines he has are basically breast lines.

He really needs to have spring lines, bow and stern lines instead of the breast lines—this is especially true in the case of having fixed docks with a tidal range. The longer lines—bow, spring and stern—will allow the boat to rise and fall without moving much horizontally—something the shorter breast lines will not. IMHO, breast lines should only be used on floating piers, not on fixed ones. The greater the tidal range, the longer the stern, bow and spring lines should be.

The time rate of change of acceleration is also know as the "JERK" :>) I am not making this up.
So let's assume the dock lines are cinched up so tight that the boat can't move, as if there were steel cables holding it in place. In this case there is no acceleration or deceleration due to the lines being slack then reaching their maximum spring elongation for the given load. In this case the force on the cleats would be related to the wave and wind force on the boat itself. So the question is are the cleats strong enough to overcome the bouyant force of the boat and force the boat deeper into the water or in the case of a wave trough are they strong enough to hoist the boat out of the water. It seems like cleat design should be such that the screws would act like shear pins and fail before the cleat ripped completely out of the deck? The other interesting phenomena is the way the stern cleats are oriented on the Catalina 30. The lines are such that they are trying to load the cleat from the side versus pulling on the length of the cleat so there is a greater bending moment on the screws versus just a shear force on the screws. The bending moment puts a large vertical force component on the washers and nuts under the deck trying to rip them out versus trying the pull the srews through the material horizontally or shearing the steel screws at deck level. Any thoughts on these comments?

 

[jibes138]

Believe it or not

Believe it or not another reason for axial loading of a cleat involves the frictional component resisting the pull from the line. Since F= muN where mu = the coefficient of friction and N equals the normal force with F = the force resisting motion of the cleat in sliding across the deck. Since the clamping force of the screws if properly torqued is quite large, and the friction coefficient of a gel coat surface with non skid pattern lets say against the underside of the cleat is propbably pretty high as well then the force resisting the line is quite large. Probably large enough to resist the line force without any contribution of the bolts in shear. Therefore I contend it is extremely important to make sure cleats are properly tightened, if the deck in the area is soft and they lose their preload or if the nuts lose a little torque then probability of failure of the cleat is drastically increased. So everybody go check your cleats and make sure they are tight.

 

[NC-C320]

Line Arrangement

From my reading of this thread, Hermit has not confirmed that he was tied up in his current dock as shown in the photo (a previous dock is in the photo, not where the damage occurred), nor as in the diagram posted. Perhaps he could let the forum know exactly how he was tied up, with what lines (size), condition of lines (new/old/good/bad), number of lines, length of lines as tied up, how he was secured to pilings (loop, clove hitch, round hitch with two or more half hitches), where fenders were, lines led how (crossed, not crossed, breast line), tide conditions, wind conditions. While he has received lots of good information in general on how he should tie his lines, analyzing this particular set of failures that gives him the damage could be more on target if he were to provide the information. Tied up properly, a C30 and other boats can experience near hurricane conditions without pulling out the cleats and breaking sufficient number of lines to allow boat to come down onto the leeward pilings (in preparing for hurricanes, it is normal to put on extra lines to alternate tie points so there is enough redundency that any given failure doesn't result in damage to the boat by drifting down onto pilings. So, Hermit, just how did you have to boat tied up?

 

[Hermit Scott]

4 bow lines, not crossed. 2 stern lines not crossed. There are pilings about in line with the transom and there is about 4' in front while the wind is pushing the boat rearward. I guess there would be about 2' of room between the dock and the bow if the wind was going from the stern, but i have NEVER seen the wind coming from that direction.
The 4 bow lines were pretty new line 1/2" anchor rode nylon, not twisted some kind of braid. The stern lines were 5/8" actual dock lines like the kind you buy in a package at walmart or west marine. I think those are some kind of polypropylene. Those were not wrapped around the cleat but fed through because the cleats are too small to accept them going around. On the bow cleats, I tied a bowline then fed the loop through the center then around the whole cleat. I am not sure how I tied the second line on to each cleat, probably which ever way it fit.
Business put me off another day from going to fix my boat. So the schedule is Saturday (tomorrow) and Sunday.
NC- I wish I had a camera to document exactly how it was tied up and just to show the gory details of a hole where a cleat used to be. I promise to have all that Sunday night.

 

[NC-C320]

Polypropylene Line

Avoid polyproplyene for dock lines. It's less expensive than nylon or polyester. Nylon, either three strand or double braid as you like, is the best dock line. It stretches to absorb shock (but watch stretch on the leeward side, because if enough stretch is present, you could hit the pilings or finger pier downwind.....I've seen lots of boats in my marina have problems with this. Polyproplyene degrades badly strength wise if exposed long to the sun, and doesn't stretch well. Not sure about abrasion resistance, but I think that is not good also. Usually (all I have seen) dock lines from West Marine are nylon. Don't know about Wal Mart, but at Lowe's and some other places, I've seen "poly" lines which are sometimes a mixture of polyproylene and other unspecified fibers. Even some lines sold as Nylon, if you read closely, are a mixture of polypropylene to keep price low --avoid these. (There's a 34' trawler in our marina now that has polyproylene lines on his stern, and unfortunately, he's going to pay the price when the bad storms come). Photos will certainly help the forum assess your particular situation if you can get them. My own opinion, and that of a several others in my marina is don't be afraid to put multiple lines (1/2" or 3/4") lines to multiple tie points on your boat. Counting on a single line or even two in somecases can become trouble if the lines chafe into or break....this is especially true in rough and windy conditions, but have as much slack as you can within your slip to accommodate rise and fall of water...crossing stern lines and using multiple spring lines can help accommodate this. If a line goes really tight and the bouyancy of the boat presses hard enough, then either the line will break or cleat will fail. Same thing happens if a line can, under one condition slip down on the piling, but as tide rises, becomes tight against the piling, refusing to slip back up on the piling. But we'll look for the photos if you can get them so as to be able to make specific comments for your case.

 

[Hermit Scott]

One thing I am not sure about is how to cross stern lines or bow lines with out them rubbing the gel coat off the deck and coamings. I considered crossing the lines last time I was down there but I know there would be NO gel coat left in those areas.

The line I bought was 100% nylon 1/2" double braid from Academy. I am going to buy another 150' of some kind of rope tomorrow, move my boat and have set docklines that I can just feed and loop around the cleats to make sure it's the same every time.
I'm leaving right now to buy some big cleats and I have 1/2" fiberglass board I will back them with along with some washers.

 

[sailingdog]

HS—

First, you really should only use Nylon for dock lines. It has the best mix of characteristics for docklines, in terms of UV-resistance, elasticity and strength. Double braid docklines are a bit stronger than three-strand, but not as abrasion resistant when dealing with old wooden pilings.

As for crossing the lines—you really should, since it will give you a lot better chances of surviving intact. To fix the problems with damage to the gelcoat, install stainless steel rub strakes to protect the fiberglass from the lines. Here is my ground tackle setup, and you can see the two rub strakes I've installed.

BTW, your cleats should be 16 times the diameter of the docklines you're normally going to use in length. If you have 5/8" dock lines, then you want to use 10" cleats. This rule of thumb allows you to use two dock lines on each cleat.

Don't use bowlines. Eyesplices are far better, since they retain far more of the rope's strength. A bowline, at best, will only retain 60% of the line's strength, where a splice would be closer to 85% or so. Splicing double braid or three-strand isn't that difficult.. so learn to do it.

As for chafe protection, go to an outdoor gear store that sells climbing gear. You can often get 1" and 2" tubular webbing there. That makes very good chafe protection.

 

[jibes138]

Eye Splices in double braid

Suggest you use my magic splicing tool when you learn how to eye splice double braid line. It is free and an inventor like yourself can make one in minutes. It is by far the best splicing tool you will ever use. I used it on my JSD to make assorted splices because i used lengths of line I got great deals on at the Defender warehouse in the back room where they sell line remnants. So my JSD has a few extra joints. The magic splicing tool is the best deal on the internet and by far the best deal in boating. If you disagree try to beat FREE. I've also used it to eye splice halyards to shackles and for dockline splices. Great tool.

 

[Cpt. Jon]

Suggest you use my magic splicing tool when you learn how to eye splice double braid line. It is free and an inventor like yourself can make one in minutes. It is by far the best splicing tool you will ever use. I used it on my JSD to make assorted splices because i used lengths of line I got great deals on at the Defender warehouse in the back room where they sell line remnants. So my JSD has a few extra joints. The magic splicing tool is the best deal on the internet and by far the best deal in boating. If you disagree try to beat FREE. I've also used it to eye splice halyards to shackles and for dockline splices. Great tool.

So, where do we find info on this tool?

 

[Hermit Scott]

cleats

I bought the cleats today. They appear to be the same kind in the saildog's pic above. These are 11 3/4" long. I like it that they have flanges to mount them instead of just holes through the middle, like the one that ripped out.
What are the twisted C shaped things near the cleats? I have one on the fore deck of my boat. Why would I have just one?
Also how do you criss cross lines with out going over the boat and chaffing it?
Saildog is the a pic of your trimaran? I have climbing gear, I will take someof the nylon tubular webbing with me in the morning.

 

[sailingdog]

I bought the cleats today. They appear to be the same kind in the saildog's pic above. These are 11 3/4" long. I like it that they have flanges to mount them instead of just holes through the middle, like the one that ripped out.

I like these cleats as they spread the load out over more surface area and more fasteners than the ones with the holes through the middle.

What are the twisted C shaped things near the cleats? I have one on the fore deck of my boat. Why would I have just one?

Those are bow chocks, and are they are designed to be line-guides and keep the lines leading fair to the cleats. A lot of boats were sold with just one to keep the anchor rode/mooring line in position. If you look at the photo, you'll see a smaller black chock on the port side, which is the original chock provided by the boat manufacturer. The original ground tackle was a single eight inch cleat. What you see in the photo is what I installed to replace the lighter, smaller chocks and the single cleat.

Also how do you criss cross lines with out going over the boat and chaffing it?

Saildog is the a pic of your trimaran?

I could cross line, but due to the narrowness of my trimaran, it doesn't make much sense. The stainless steel rub strakes are designed and placed to protect the fiberglass from line abrasion.

I have climbing gear, I will take some of the nylon tubular webbing with me in the morning.

Good idea.

 

[txtowman]

where do I find this splicing tool?