Compartment Drain Plugs?

[Addicted]

I agree, except that our boats are designed with a psuedo double hull. The interior hull being the one with all the drain plugs we are discussing.

Either way, if you are continuously taking on water so bad that the bilge pumps can't keep up, you're screwed. Which is why I have two bilge pumps. I believe plugs in gives you time, nothing more. Less time with plugs out.

You could be right, but how? Isn't the water coming in at the same rate? Your just keeping it in the back of the boat is all. How does that buy time?

I agree on the additional pump. I love redundancy for the sake of peace of mind. I hope to never need it, but will be thanking my lucky stars if I do!

Wow, really?

I am entirely sure of how the physics works. I'm entirely sure I don't like the tone of that remark. Go ahead and leave all your plugs out. You'll be fine.

I am sorry to have offended you. It was not my intention, but I sometimes struggle to get my thoughts written out/represented clearly. I agree with your earlier comment that this would be a good topic to be discussed over a few beers rather than a keyboard. My apologies.

 

[upperdeck]

It comes in faster through all your open plugs, vs slower when all those openings are closed. Also, if you are taking water over the bow, open plugs diverts water into the bilge to pump out, bypassing the scupper.

 

[Addicted]

The water is not coming into the boat though all those open plugs. Only one plug allows water intot he boat. That one should always be installed while in the water, no argument. The rest of the plugs simply keep the water in the back of the boat. So, if you have water coming into the boat from a hole, or broken scupper, or whatever, the size and location of that hole is what determines how much water is coming in. Back to your bathtub analogy, with the 10" dividers with plugs in them as I described, you have a puncture, lets say you were to release the plug as you said, because of the 10" dividers with plugs in them, the water is going to enter the tub at whatever rate the puncture allows. With the dividers, and plugs in place the water is going to settle at one end of the tub until the water level gets high enough to pass over the divider, then it will begin to fill that cavity until it reaches the top onf that 10" divider, and so on. The tub will settle low in the water at whichever end the water is coming in (lets say it is the rear). So the stern is low and bow is high, and the water is continuing to rush in until the water outweighs the displacement, or until the rear edges of the tub are sitting low enough to start taking water over the top.

Now, same scenario with no plugs in, you pull the plug and the tub fills up at the same rate as before (cant come in any faster than the puncture will allow), but the water is now being spread evenly through out the tub. The tub is now sitting level but sinking lower in the water. Either way the water is coming in at the same rate. In fact it may hold more water because it is sitting level and the rear is not sitting even lower than the front.

In the scenario above, my thought is to protect your vitals. Motor (for power and charging) and electrical (for bilge pump and radio). If the boat is sitting level while taking on that water, won't you have access to your vitals for a longer period of time? Don't get me wrong, I know your already screwed at this point, but I am using that scenario to argue that there is no benefit to having the plugs in, and may even be a benefit to having the plugs out.

As far as the scupper is concerned, when you get water in the boat, most of it will travel along the deck and out the scupper as you mentioned, which a great design that these boats have. But much of that water will roll down the sides of the hatch for the ski locker and fuel compartment into a gutter system that leads back to the scupper. As this gutter system gets full, by either too much water at one time, or getting backed up at the scupper opening (it can only drain so fast), it overflows into the ski locker and fuel tank compartment. That water can never get to the scupper and needs to drain out through the plugs and into the bilge to be pumped out. Having the plugs in or out of the compartment drains has no effect on how much water will make it to the scupper.

 

[upperdeck]

I disagree that no water would come in through the open plugs. If you have a hull breach, and your plugs are open, water would most definitely enter through the interior plug holes.

I agree with your scupper comment, except if there is standing water in the boat. If there is standing water, the ski locker will fill (doubtful about the extent of the fuel cavity since there is a rubber seal under your floor). If your ski locker port is open, water will drain into the bilge, bypassing the scupper. In that scenario, instead of having the both bilge and scupper draining your boat of water, you are forcing more water to the bilge pump.

I think we simply need to agree to disagree.

My parting comment... If Yamaha (and the rest of the industry for that matter) with all their R&D dollars agreed with your scenario, why wouldn't they just leave ALL the drain ports open? Why factory install closable plugs in the first place? Your boat came loaded with liability stickers. They are obviously concerned about the use of their product by the end user. Yamaha directs the plugs to be installed.

Peace

 

[Addicted]

I disagree that no water would come in through the open plugs. If you have a hull breach, and your plugs are open, water would most definitely enter through the interior plug holes.

I agree with your scupper comment, except if there is standing water in the boat. If there is standing water, the ski locker will fill (doubtful about the extent of the fuel cavity since there is a rubber seal under your floor). If your ski locker port is open, water will drain into the bilge, bypassing the scupper. In that scenario, instead of having the both bilge and scupper draining your boat of water, you are forcing more water to the bilge pump.

I think we simply need to agree to disagree.

My parting comment... If Yamaha (and the rest of the industry for that matter) with all their R&D dollars agreed with your scenario, why wouldn't they just leave ALL the drain ports open? Why factory install closable plugs in the first place? Your boat came loaded with liability stickers. They are obviously concerned about the use of their product by the end user. Yamaha directs the plugs to be installed.

Peace

You do understand that the compartment plugs to not lead to the outside right? They simply lead to the next compartment (from the ski locker to the fuel tank, from the fuel tank to the engine compartment). I am only commenting on my model, as I am not familiar with other models, and as Mel stated, the 230 is different, however the compartment plugs on the 230, do not lead outside of the boat either. I wont pretend to know all, but I will say without hesitation that there is only ONE plug that allows water into the boat. That plug needs to be regardless. Therefore the volume of water that can enter the boat is dependent solely on the breach. Additional water cannot enter the boat because the compartment plugs are installed, period.

This may sound sarcastic, and I assure you that is not my intent, but next time your hanging out in the boat drinking beer, doing nothing important, I recommend that you take a few minutes to investigate the way the drainage in our boats is designed. The gutter system, the scupper, the compartment plugs. It really is a good system, but the more you know about the way your boat works, the better. Again, not intended to be sarcastic, but based on your comments above, I am thinking that you have not had the opportunity to educate yourself on the way these boats drain. Please do not take offense to that!

As far as Yamaha is concerned, they also say the plugs don't blow out. Just because they are there and Yamaha says to do, does not mean it is the best answer.

 

[upperdeck]

Now you're just being insulting. Of course I know my boat and how it drains water. Yes I know that no more water can enter the boat than a breach allows. Common sense (perhaps not so common) says that you want to slow the entry of water above the interior plugs. You are doing the opposite by keeping the plugs open. Its really quite simple.

You may note that no one is disputing the Yamaha guidance about plugs in or out in this thread other than you. It seems to me that you may be lacking in understanding. I won't insult you by claiming that I mean no sarcasm.

Please don't direct any more comments towards me. I'm not looking for a dispute.

 

[4x15mph]

I am hoping to see how this ends since I don't have any engine compartment or ski locker plugs. They were not there when I bought this from the previous owner. I did find a screw in plug at Walmart that I plan to get around to trying. If I hear I need these, I will spend more time on this

 

[maboat]

I am sorry to have offended you. It was not my intention, but I sometimes struggle to get my thoughts written out/represented clearly. My apologies.

Thanks for the apology. Let me see if we can dig out of this rut I am going to attempt another explanation. If you want to learn, great. But if you just want to debate it, I'm not interested. These are facts, not theories

@txav8r summed it up pretty good (as usual ) There are a few different topics intertwined here. Regarding the compartment drain plugs, most of the time when there is nothing otherwise wrong with the boat, it doesn't matter much if they are in or out. Personal choice really. But I think its safe to say the general consensus (which was the original question I believe) is boat in water, plugs in. Boat out, plugs out. Of course that is a generalization. If the ski locker fills with water, well of course pull the drain plug to drain it. Nobody says it has to absolutely stay plugged at all times while on the water.

I see your train of thought in the bathtub analogy and I don't know how else to say this, but it is flawed. When it comes to extended buoyancy in an emergency situation, the plugged compartments do make a difference. Its absolutely possible for an open-at-the-top compartment to fill (but not overflowing) with water and the boat (or tub) still floats. This was the situation with the Titanic. It could still float with some number of (I believe it was 3) flooded compartments. The iceberg cut a slice in more (4 or 5 ) compartments and that simply exceeded the design limitations. In the bathtub analogy, it all depends on how big the compartments are. I'm not sure where the 10" came from, but that could be plenty if the compartments are not too large. You mentioned displacement, so I know you have some of the concepts. But here's the part you're missing: as long as each compartment holds no more water (in weight) than the weight of the compartment itself, then it won't continue to sink and it won't spill over the top flooding the next compartment. I wish I could draw a picture of the bathtub. Picture the Titanic with its walled (but open at the top) compartments. Now instead of an iceberg that sliced through the side of 4-5 compartments, lets say there was a torpedo that put a big hole in one compartment. That compartment would have taken on water, but only as much as the weight of that compartment itself. Water would rise to a certain level, but as designed, it would not be enough to reach the top. It would have stayed afloat. So would the bathtub. Both the Titanic and the bathtub would continue to float with a hole in the bottom of one compartment even though all the compartments are open at the top. Our boats are the same - as long as the compartments are plugged. If the Titanic had open doors in the lower level of all compartments (similar to having all drain plugs out), just one hole in one compartment would eventually sink the ship

My point about the cleanout tubes is that they are themselves a small compartment with an open top. I mention them because I though it was an easy-to-see example of this principle. When you remove the cleanout plug, you are opening a big hole in the bottom of the boat. Water rises in the tube only high enough to match the water level outside the boat (which is determined by the weight of the boat and the weight of the water it displaces). The water rises no higher and does not spill over the top of the tubes (not counting the splash in the face you get if the water is choppy ). Imagine now if the cleanout tube had a drain plug at the bottom of the tube that drained into the bilge and you left that drain plug out. Now remove the cleanout plug. It would not be good. The same principles apply to all compartments. Individually, each compartment does not hold enough water to weigh the boat down to the point of sinking or flooding over the top. But if all the plugs are out, you have one big compartment of water that will be too heavy for the boat to remain buoyant.

Besides all that, its not like the engines will instantly die as soon as water touches them. Its only if the water gets up to the top of the engines where the air intake is. Now here I'm going to speculate (theory, not known fact), but its very possible that if you keep the engine compartment plugged. The water may only fill up to a point just below the intakes. Yeah I know its still a scary thought, but the less water you allow into other compartments, the less deeper you will sink in the water and the lower level of water in that one contained compartment.
Hopefully this all sheds a bit more light on it for you If it does, then you may owe me a few beers

and if not, then its not the end of the world either. I'm not trying to convert anybody to my religion.

 

[Addicted]

Actually your response is very helpful. A few beers I do owe you, thank you.

 

[paul075]

I am going to put in my $.02. In my 12 SX210 there are foam filled cavities in the rear of the boat outside the clean out plugs under the rear swim platform. I have seen these when installing my second bilge pump. I am also pretty sure there is more foam under the cockpit port and starboard of the ski locker and gas tank compartment. My point is that with the ski and gas tank drains closed I don't think you could take on enough water to overflow the top of them. Buoyancy is king and the amount of air inside those 2 closed compartments could very well be the thing that gets you to the beach and not sunk.

 

[Zarrella]

Who wants to donate a boat to try this theory out???

 

[Magic]

It's Magic.

Huh, What? What'd I do now???

 

[Magic]

OK, here is my take....

Our plugs are closed in the water, period. Rational being experience. If you take in water (as in a sub move, or a wave over the front as in large waves off-shore) you flood the deck area, and the water fills the ski compartment and the deck area. The liner is built up to contain that water to a certain extent. That water will drain relatively quickly out the scupper as it is designed to do. If the ski (and other compartment) plugs are open, that water drains into the engine compartment or rear area of the true bilge, where it will be removed, rather slowly in comparison, by the bilge pump, or not at all in the true bilge. The risk is having the deck contained water drain into the lower level engine compartment, and not only possibly damaging the engines, but also creating a weight distribution that may swamp the rear of the boat where most of the weight is already, allowing enough new water in over the back to cause a capsize.

Notice that the motor of this exciter keeps running even with a deck full of water. The engine compartment was isolated from the water coming in over the bow in the sub move. Imagine if that water was allowed to flood into the engine compartment through open plugs.....

Separating that scenario from a below waterline puncture is essential in understanding the purpose of the deck liner and scupper relief system.

There is, or used to be, a thread from 2005 or so at YJB that had a diagram about this....

 

[Gym]

OK, here is my take....

Our plugs are closed in the water, period. Rational being experience. If you take in water (as in a sub move, or a wave over the front as in large waves off-shore) you flood the deck area, and the water fills the ski compartment and the deck area. The liner is built up to contain that water to a certain extent. That water will drain relatively quickly out the scupper as it is designed to do. If the ski (and other compartment) plugs are open, that water drains into the engine compartment or rear area of the true bilge, where it will be removed, rather slowly in comparison, by the bilge pump, or not at all in the true bilge. The risk is having the deck contained water drain into the lower level engine compartment, and not only possibly damaging the engines, but also creating a weight distribution that may swamp the rear of the boat where most of the weight is already, allowing enough new water in over the back to cause a capsize.

Notice that the motor of this exciter keeps running even with a deck full of water. The engine compartment was isolated from the water coming in over the bow in the sub move. Imagine if that water was allowed to flood into the engine compartment through open plugs.....

Separating that scenario from a below waterline puncture is essential in understanding the purpose of the deck liner and scupper relief system.

There is, or used to be, a thread from 2005 or so at YJB that had a diagram about this....

How do you know whether the plugs were in or out in this instance? The plugs we're talking about are only 1/2 inch whereas the bilge outlet is 3/4 inch so the water going into the engine compartment would not be more than the bilge pump could handle. The deck drain would also handle most of the water. Only what got beneath the deck would have to be handled by the bilge pump. If the plugs were in, the bilge wouldn't get much water to pump out.

Most water incursions we hear about are through the engine compartment either due to a clean out plug blowing/dislodging or a broken cooling/exhaust water clamp. That is where you are most challenged to mitigate the problem before it compromises the engines.

Yamaha specifies plugs in while in the water but they live in a perfect world where clean out plugs never blow out, they are only installed incorrectly. Stainless steel clamps never break because, well, their stainless steel but we're the test dummies that live in the real world.

I had a real world experience when, during my first year, I launched with the drain plug out and bilge pump off (newbie mistake) drove it a mile to the dock, tied it up and started back to the house when I remembered I hadn't turned on the bilge pump. When I did and saw the water being pumped out I knew exactly what I had done. I grabbed the spare plug out of the glove box and dove into the frigid water. After replacing the plug I got back on board and opened the engine compartment. The water was half way up the oil pan. I thought, that wasn't much water for all that time. Then I looked in the ski locker. It was almost 3/4 full. I then realized if I had the plugs in ALL that water would have been in the engine compartment and the outcome would have been very different.

My plugs are out while in the water. I'm not trying to convince others to do the same but I learned the hard way that it worked for me. Aside from using a checklist now the only other thing I may consider changing would be to change the main drain to a one way drain like this: http://www.overtons.com/modperl/product/details.cgi?pdesc=One-Way-Safety-Plug&i=71746

 

[davel501]

Do we know the boat will sink far enough to flood the engines if the forward compartments are water free? We need a boat that is already a total loss or someone that has a friend that is an engineer at Yamaha. Either way we also need a whole bunch of beer because thoroughly testing these scenarios is not possible if we are making good decisions.

 

[txav8r]

@Gym , the clean out plug blowout will not flood the boat...unless you try to keep going! All you have to do to stop water with a plug blowout is STOP the boat, and the water stops. There is no possible way to prepare for every scenario without setting yourself up for consequences from something else. And on the forgotten drain plug, well, you forgot something important and keeping the plugs out for something that should be automatic...not sure I understand that. Had your bilge pump been on (as it should have been), then it would have been pumping the water that the transom drain was letting in. But with all the plugs out, had you not remembered, as water crept forward, the bow would sink as the ski locker filled, and the stern would rise, separating the water from the bilge pump.

 

[Gym]

@Gym , the clean out plug blowout will not flood the boat...unless you try to keep going! All you have to do to stop water with a plug blowout is STOP the boat, and the water stops. There is no possible way to prepare for every scenario without setting yourself up for consequences from something else. And on the forgotten drain plug, well, you forgot something important and keeping the plugs out for something that should be automatic...not sure I understand that. Had your bilge pump been on (as it should have been), then it would have been pumping the water that the transom drain was letting in. But with all the plugs out, had you not remembered, as water crept forward, the bow would sink as the ski locker filled, and the stern would rise, separating the water from the bilge pump.

Mel, I accept your critique of my compound newbie mistake but I respectfully disagree with your weight and balance assessment. Assuming the bilge pump is off and compartment plugs are out as the water enters the lower bilge it will lower the stern of the boat. As water creeps forward into the engine compartment the stern will get heavier and lower in the water. As water continues forward into the fuel tank section and ski locker the boat will get lower in the water but the bow will come down as the balance will equalize. There would never be more water in the bow than the stern unless you were very bow heavy to begin with.

 

[Magic]

Ive come around on this issue, and since its going to be near 100 here, im going to put the plug in the ski locker IN, fill it with ice, and beer for ballast of course, and ponder the Mysteries of the Universe with The Girl this weekend......

If the phone doesn't ring......it's me.

 

[txav8r]

May be so @Gym, but I don't believe the theory that letting it fill up the fuel and ski lockers will add any benefit vs not letting it. While in theory, I can see a point of topic for a low stern to begin with as this happens, it doesn't take much water before it is spilling from the engine compartment through the bulkheads and under the seats, then out of the engine compartment into the cockpit floor and forward. I doubt if in either case, plugs in or out, that the boat would sink completely, but time wise and amount of gunwale above water, preventing those big compartments from filling makes sense to me and apparently to Yamaha as well. We won't solve this debate or get a general consensus on it here today or in the future, our visions are not far reaching enough as individuals. I am willing to bet also, that the "rookie mistake you made (we all have made them at some point, right?), isn't a mistake that you need to plan ahead for again! Once you leave the clean out plugs out for a launch, it becomes just as important to you as the transom drain plug would be! The thing is, you take on zero water with that transom drain plug open when up on plane and running. But the entire time your motoring out of the no wake zone, your boat is drinking in the lake! And like the cockpit drain system that feeds the scupper valve to drain the cockpit area, it does it when on step too. I wasn't a physics major, but I love physics, and I am not an analyst but I love analyzing these situations. Even the rookie mistakes I made that I am sure caused me to overcompensate too, eventually fade and while we remember them, they don't cause the anxiety that they previously did. Heck, I took all the media I could get my hands on and compiled it into checklist form and used it religiously...but not forever. Besides, I already know you guys are smarter than me...I was stupid enough to sell my boat.

 

[Julian]

Fascinating discussion folks....feel obliged to add my 2 cents of summary:

1) Regardless of plugs in or out, a hull breach will result in a swamped boat and engines submerged. It won't sink for something like 24-48 hours (that is a coast guard requirement and yamaha has to test that).
2) Leaving the plugs in will (in my opinion) slow down the progression of reaching that submerged state. Using the bathtub analogy, this boat is really a big bathtub with a small one inside it (the ski locker--is all glassed in and sealed - as is floor coolers on those with them). As such, if the inner bathtub is sealed, it will add buoyancy until such time as the weight of the boat over loads it, and water enters over the top of the walls.
3) Some have made the point that plugs out will give you more time to avoid swamped engines as it will give the water somewhere else to flow. Interesting theory. It only helps you if you are on the boat and find the problem before the engines are swamped. I think I'd rather have the added buoyancy of the ski locker to float the boat longer than the added time to avoid a swamped engine when I'm in the boat. That is personal choice and will yours will vary depending on if you ever leave your boat unattended in the water. Many who trailer do not ever do that.
4) @txav8r I disagree completely with your assertion that a blowout will only sink a boat if they keep running the engines. If you have a blowout that dislodges the bottom of the clean out tube "hose" and have already taken on some water, the metal flange at the bottom of the cleanout can be below water. So at this point, you are going to sink with the engines off. This kind of blowout where the plug lodges in the tube and blows the hose off the bottom is the most dangerous kind and can sink you. A much better design from Yamaha would be to extend the metal of the cleanout up a foot, or all the way to the hatch to prevent this (or to make a plug that doesn't blow out!).

All of that said, I really don't pay much attention to my internal plugs. I try to keep them in, but I've removed the critical one (ski locker) to let it drain and forgotten to put it back in a number of times. Then engine ones are, in my opinion, only there to drain water once it gets in there. On the LS2000 series, the engine bay was much better sealed (the bilge pump was...drum roll...in the BILGE) but now the 230+ boats it isn't.

Great discussion, and I think the conclusion for me is.....keep the ski locker plug in so she'll float longer if she starts taking on water when I'm not there. If she starts taking on water when I am present, my bilge alarm will go off, and I will race for shore.