Plugs Out: Normal Water Level in 17 Montauk at Mooring

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Beerspitnight
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Plugs Out: Normal Water Level in 17 Montauk at Mooring

Postby Beerspitnight » Sun Jun 12, 2016 2:35 pm

Hello All. After arriving back home from China on Wednesday night I was able to splash my 1989 MONTAUK 17 last night after working on the boat for a full two and a half days (I'll post a narrative about that work later this week).

In the past, I have always left the drain plug in the boat, but decided to remove the plug this time around per the advice posted on this site and via the Boston Whaler user manual. I expected there to be four to five inches of water in the stern with the plug out. What I was not expecting was the 8 to 10 inches of water that eventually filled the boat. The water was one inch below the top of the splash well. The water was sloshing up past the front of the console. The stern of the boat was sitting four to five inches below the normal waterline.

Some context: The boat is powered by a 2003 Suzuki DF70, the battery is located under the RPS, as is the 12 gallon plastic gas tank. I had 9 gallons of gas in the tank, which weighs roughly 60lbs. The battery did not move as it is secured to the deck, whereas the gas tank is not. The amount of water in the boat resulted in the gas tank floating around back of the boat.

I should have taken a photo of the situation, but I was more inclined to stop this by inserting the drain plug, turning on the sump pump, and bailing the boat out with a bucket.

Does anyone have any thoughts on this? Is the situation that I described reason for worry?

Thanks in advance.
Brian
1989 MONTAUK 17

Beerspitnight
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Re: Plugs Out: Normal Water Level in 17 Montauk at Mooring

Postby Beerspitnight » Sun Jun 12, 2016 5:53 pm

Here is an image of the boat in the water with the plug in.
I add this photo as a reference point for the waterline with the plug in.
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1989 MONTAUK 17

Wweez
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Re: Plugs Out: Normal Water Level in 17 Montauk at Mooring

Postby Wweez » Sun Jun 12, 2016 7:27 pm

[The] very heavy four-cycle engine weighs close to 400-lbs. Two-cycle 70 or 90-HP engines weighed 270 to 325-lbs. Price of green PC.

jimh
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Re: Plugs Out: Normal Water Level in 17 Montauk at Mooring

Postby jimh » Sun Jun 12, 2016 10:28 pm

I don't know if I could have stood by and waited for the water to rise to 10-inches deep in the cockpit. I would like to see a picture of that. I would have put the plug in as soon as it spilled over the cockpit sump and began to flood the cockpit deck.

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Re: Plugs Out: Normal Water Level in 17 Montauk at Mooring

Postby Beerspitnight » Mon Jun 13, 2016 6:06 am

Any ideas on what [is causing the water to rise to 10-inches deep in stern of the cockpit when the plug is out]?
1989 MONTAUK 17

jimh
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Re: Plugs Out: Normal Water Level in 17 Montauk at Mooring

Postby jimh » Mon Jun 13, 2016 6:29 am

When the cockpit sump drain is open, seawater will enter the boat until it rises to the the water line. The more water that comes into the cockpit, the heavier the boat becomes, the lower the hull sits in the water, and the higher the water line becomes. The lower the hull sits in the water the more buoyant force is created. The water continues to flow into the boat, increasing its weight, the hull continues to sink lower into the water, producing more buoyant force, until the system reaches an equilibrium, that is until the hull has displaced enough water to support the weight. Apparently on your boat, with its hull and its engine weight, this equilibrium does not occur until the water is 10-inches deep in the stern of the boat. This indicates that the amount of weight on the transom and in the stern of the boat is much greater than the boat was designed to handle. The boat was designed originally so that if the plug were not in place the water line would be just below or just at the top of the aft cockpit sump.

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Re: Plugs Out: Normal Water Level in 17 Montauk at Mooring

Postby jimh » Mon Jun 13, 2016 6:55 am

Let us try to estimate the weight of the water that will be in the cockpit of a MONTAUK 17 if the water depth at the transom is 10-inches and the water extends forward to about the center console. We can make a rough estimate of the volume as follows:

--the width of the cockpit 5-feet

--the distance from transom to console is 8-feet

--the depth of the water is 0.83-feet

This is a rectangular volume of 5 x 8 x 0.83 = 33-cubic-feet. Since the depth at the forward end is 0-inches, we slice this in half, for a volume of 16.6-cubic-feet.

The density of water is about 62.3-lbs/1-cubic-feet, so the weight of the water in the cockpit was

62.3-lbs/1-cubic-feet x 16.6-cubic-feet = 1,038-lbs

The hull of a Boston Whaler MONTAUK 17 has a swamped capacity rating of 2,000-lbs. This suggest that there was reserve buoyancy in the hull, but we must also take into consideration the distribution of the weight. The weight would most likely need to be evenly distributed as that rating of 2,000-lbs swamped capacity was probably measured with the hull evenly trimmed, not down-by-the-stern. Because the boat is not floating with even trim due to the heavy engine weight, there is no telling how much more reserve buoyancy remained.

Having that much free moving water in the cockpit creates a further problem: concern about stability. Having 1,000-lbs of sloshing water in the cockpit is going to create instability, possibly leading to even more water coming aboard if the boat rolls heavily and water comes over a gunwale.

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Re: Plugs Out: Normal Water Level in 17 Montauk at Mooring

Postby jimh » Mon Jun 13, 2016 7:16 am

Let us also consider the question posed in the initial article in this thread:

Is the situation that I described reason for worry?


If this were my boat, I would be concerned that the boat is no longer self-bailing and cannot be left with the cockpit sump drain plug removed. Any water that collects in the cockpit from rain will have to be pumped out by the electric sump pump. The boat will need a reliable sump pump and a high-capacity storage battery to operate the pump.

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Re: Plugs Out: Normal Water Level in 17 Montauk at Mooring

Postby jimh » Mon Jun 13, 2016 9:48 am

Wweez wrote:[The] very heavy four-cycle engine weighs close to 400-lbs.


The weight of a 2003 SUZUKI 70-HP engine is 341 pounds. There is no reasonable basis to consider that as being "close to 400-lbs."

Wweez wrote:Two-cycle 70 or 90-HP engines weighed 270 to 325-lbs.


An Evinrude three-cylinder 920-cc 70-HP engine with power trim weighed 250-lbs

Wweez wrote:Price of green PC.


Modern outboard engines are not manufactured to conform to political correctness, but rather to comply with federal law and regulation.

Beerspitnight
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Re: Plugs Out: Normal Water Level in 17 Montauk at Mooring

Postby Beerspitnight » Mon Jun 13, 2016 10:00 am

Thank you for the insight, Jim.

Perhaps we can speculate as to the cause of the the buoyancy concern?
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jimh
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Re: Plugs Out: Normal Water Level in 17 Montauk at Mooring

Postby jimh » Mon Jun 13, 2016 10:08 am

I don't think that the weight of the 2003 SUZUKI 70-HP four-stroke-power-cycle outboard engine is particularly alarmingly high for the boat. Many people have re-powered MONTAUK 17 boats with an E-TEC 90 engine that weighs 320-lbs. I cannot recall any actual reports of how those boats with a 90-HP E-TEC behaved with the cockpit sump drain plug out, but I would be surprised that no one has reported a problem like this if, indeed, it occurs. To have an engine that only weights 21-lbs more and causes this outcome is really a surprise to me.

Perhaps what is happening here is the transom weight on this particular boat is at a tipping point, that is, it is just heavy enough to start water coming into the cockpit. Once water starts to flow in, the weight of the water seems to be increasing faster than the hull can create new buoyant force for some time. A hull has reserve buoyancy if the hull form widens or flares out as it sinks deeper into the water. Perhaps the hull form on the MONTAUK is rather straight-sided at the normal water line, and the hull does not begin to create reserve buoyancy very fast until it sinks lower. Eventually, the hull sinks down enough to the point where the hull form begins to create buoyancy faster than the incoming water creates weight in the boat. That is when the water stops rising.

Some experimenting may be interesting. For example, remove 20-lbs from the stern of the boat. See what effect it has. I don't think this situation is going to be a strictly linear equation, that is, removing 20-lbs might have much more effect than you'd think. It could cause a significant difference in the equilibrium point. Or, at least, it is worth a try to see what does happen.

Other ideas to try:

--move the fuel tank to be forward of the console

--move the battery to be inside the console

--remove any extra weight from the stern area

IMPORTANT AFTERTHOUGHT: when the water rose to be 10-inches deep, were you still in the boat and standing in the stern?

Beerspitnight
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Re: Plugs Out: Normal Water Level in 17 Montauk at Mooring

Postby Beerspitnight » Mon Jun 13, 2016 10:25 am

jimh wrote:
Some experimenting may be interesting. For example, remove 20-lbs from the stern of the boat. See what effect it has. I don't think this situation is going to be a strictly linear equation, that is, removing 20-lbs might have much more effect than you'd think. It could cause a significant difference in the equilibrium point. Or, at least, it is worth a try to see what does happen.

Other ideas to try:

--move the fuel tank to be forward of the console

--move the battery to be inside the console

--remove any extra weight from the stern area


A sound plan, Jim.

I will play around with the distribution of weight later this week. I will take photos and detailed notes so I can share my results with the forum.
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kwik_wurk
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Re: Plugs Out: Normal Water Level in 17 Montauk at Mooring

Postby kwik_wurk » Mon Jun 13, 2016 3:55 pm

You will have (up to) a few inches of water in the back deck with plugs out. If you are ALSO standing in the stern area, you will definitely have several MORE inches of water, depending on how much you weigh. But 10-inches of water in the cockpit is more than expected. Look at what is in the bow locker and what is in the console. [Move the boat] battery forward.

With the plugs out and the weights listed below I experienced three to four inches of water in the aft cockpit area [of some unspecified boat]:

--Mercury 90, 305-lbs and 18-lbs SS propeller and full oil tank
--Mercury 6-HP auxiliary, 53-lbs
--22-gallons fuel, 153-lbs
--two Digi-Troll IV downriggers on aft most railing, 40-lbs
--Optima Blue Top battery in console, 38-lbs
--three downrigger balls in bow locker; 28-lbs
--anchor and chain in bow locker, 25-lbs
--miscellaneous weights in bow locker, 5-lbs
--miscellaneous gearl 60-lbs in console and foredeck
--cover, 10-lbs

TOTAL is 735-lbs of weight, most of which is in the aft one-third of the boat.

The recommendation of plugs-out is ok for a lake boat with nothing in it, but most cases it's a real problem for trim--not to mention the green stuff that will grow on the interior. I have had up to 10-inches of rain water in my boat; that is part of the reason why my battery is in the console and on the console base board itself.

Generally speaking the boat is ok with several inches of water underway, but stationary it is suspect to a slow roll. You can't stand or stay on one side, otherwise the water will simply go to that side. And it's hard to correct for--but this is true for any boat. With 10-inches of water, you must be prudent when walking around.

hauptjm
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Re: Plugs Out: Normal Water Level in 17 Montauk at Mooring

Postby hauptjm » Mon Jun 13, 2016 5:07 pm

I have a 1985 Outrage 18, and I, too, would have been very concerned with that much water rising in my boat without the plug. Since my reference point is slightly different--18 Outrage v. 17 Montauk--I believe the intended design function would be generally similar. With a modern two-cycle 150-HP (Evinrude E-TEC) set back 12-inches off the stern--adding to the effect of the engines weight--on a hydraulic jack-plate--more weight--and two batteries at the transom, along with a fiberglass cap that forms the full transom stern--even more weight--the water level is approximately 2-inches below cresting the sump into the deck area. If I (195-lbs) stand right over the sump, I'll bring in an amount of water that is approximately 2-inches deep across the stern wall of the cockpit that extends out (forward) in declining depth for 4 to 5-inches.

I have fished my boat with a friend and forgot to put in the plug, and, other than occasionally getting my feet a little wet, we never bothered with it. My fishing buddy was a little dismayed at first, but within a few minutes realized that it was no big deal. With that said, you should not have anywhere near that amount of water in your boat at rest, with the described systems. I would be very conscious of the chance you may have water intrusion into your hull. Your Whaler is nothing more than surf-board with a motor. I'm not trying to trivialize your dilemma, but imagine the forces need to push that board underwater. If you compromise the flotation of the board then its buoyancy with be reduced.

Maverick
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Re: Plugs Out: Normal Water Level in 17 Montauk at Mooring

Postby Maverick » Mon Jun 13, 2016 6:08 pm

Brian--have you considered trailering [the boat] to a scale like a CAT-Scale truck stop to see what the rig weighs?

Launch boat and take trailer back and weigh, subtract, then subtract motor and battery to determine bare hull boat weight. Compare that weight against the specification. The information may help you make a decision on [where you locate the boat] battery.

Knowing the bare hull weight can help you understand and properly assess what you are observing.

The Montauk is a great boat. I've owned a few and even tried to sink one--hah--some years ago in a wailing gale. It showed me and kept on going and got me home safely in spite of my poor weather planning.

--Mav

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Re: Plugs Out: Normal Water Level in 17 Montauk at Mooring

Postby Beerspitnight » Tue Jun 14, 2016 6:19 am

Thanks for all of the responses and input.

jimh wrote:
IMPORTANT AFTERTHOUGHT: when the water rose to be 10-inches deep, were you still in the boat and standing in the stern?
- I was not standing in the stern at the time although more water entered the boat once I got into the boat.

I am unsure where water would have ingressed into the hull; The boat did not have bottom paint on it when I purchased it, and I did not see any damage or repairs to the hull before painting it for the first time. There are some old screws in the transom where a transducer was located. Those screws are still in place and there is evidence that a sealant was used around the screws. It is possible that the sealant is not sufficient and water has entered the hull from those screws.

Additionally, I had to repair some keel damage due to a beaching. However, that damage wasn't very deep and appeared to only be cosmetic. http://continuouswave.com/forum/viewtopic.php?f=6&t=803&p=6386#p6386

I am only home for 7 weeks this summer, so I will consider weighing the hull when I pull the boat at the end of my boating season. I can get the trailer weighed before pulling the boat.

We will also play around with weight distribution and will document the effects.
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leadsled
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Re: Plugs Out: Normal Water Level in 17 Montauk at Mooring

Postby leadsled » Tue Jun 14, 2016 9:47 am

I don't think the 16-17 hulls float high enough to have no water above the sump like the c.1980 Outrage 18. I had a 1967 bare hull 16 with two Tohatsu 8-HP two-stroke-power-cycle outboard engines (130-lbs) and a battery. Water still came above the sump. My 1989 Outrage with a E-TEC 115 and Tohatsu 8-HP floats high enough so no water goes above the sump. My c.1960 Standard 13 with a 8-HP Tohatsu floats high with barely any water on the floor.

Whalers are self bailing but not all of them float high enough to keep the floor dry. The weight of engine and equipment makes a difference.

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Re: Plugs Out: Normal Water Level in 17 Montauk at Mooring

Postby jimh » Tue Jun 14, 2016 9:48 am

You can probably weigh the trailer (without the boat) by using a bathroom scale. Measure the weight at each wheel and at the tongue jack stand. Add the three weights. That's how much the trailer weighs.

For advice on how to weight a boat on a trailer at a CAT Certified truck scale, see this prior discussion:

Boat Weight From Certified Scale
http://continuouswave.com/ubb/Forum1/HTML/016667.html

The above article will give you detailed advice on how to use a truck scale and how to use the data you will get to calculate the weights of various parts of the rig.

The general outcome of taking your Boston Whaler boat to a truck scale and getting weight measurements is to discover that the weight of "the boat" component is greater than the initial estimate.

When you get that result, remain calm. The weighing is not going to give you great insight. You have no idea what the hull actually weighed when it was made. Yes, there is a specification, but not every hull ever made weighs exactly the specified amount. And you have no idea exactly what components were installed on the hull when it was supposed to weight what the specification called for. There is no reasonable basis to attribute the higher weight to absorption of water into the foam interior of the double bottom hull.

For advice on water in the hull, see the answer in the FAQ at

http://continuouswave.com/whaler/reference/FAQ/#Q3