Floor height, 70's rebuilds

[MarshMarlowe196]

MM:  Doesn't matter if your floor is sealed if scuppers are under water and they fail.  they let in more and more water, and sooner or later the boat is swamped... even if the bilge is bone dry.

I have to ask- have you ever seen this happen?  My thinking is the only way this could happen is either your entire floor deck is below the waterline, or the incoming water would have to travel uphill.

I haven't seen many "self-bailing" boats, new or old, that actually work the way they're supposed to.  Furthermore, I haven't seen a scupper (no seacock) that completely seals the water out (even the ping pong style will let a little water in slowly).  If boats were sinking because of scuppers being below the waterline, half of all supposed self bailing boats would sink at the dock- it would be an epidemic.

I've left a 1720 KW with scuppers below the water-line (no ping pongs, duckbills, flappers, etc.) moored over the weekend with water in the stern that came through the self-bailing drains, and the water level stayed the same.  Done the same with my Aqua- the water stops at the waterline.  It's simple displacement.

I guess I could be wrong about this, but I've never seen it happen myself.

[RickK]

Guys, interesting point the rebuilder brought up yesterday. He said he was going to put a slight crown in the deck, highest forward to aft down the centerline of course, so that water on the deck naturally drains to the sides and then to the stern.

Like a football field, pretty basic I guess, but yours truly dum-dum didn't think of that.

That's how the originals soles are - seemed to be high going down the middle so the water ran to the sides.

[LilRichard]

Guys, interesting point the rebuilder brought up yesterday. He said he was going to put a slight crown in the deck, highest forward to aft down the centerline of course, so that water on the deck naturally drains to the sides and then to the stern.

Like a football field, pretty basic I guess, but yours truly dum-dum didn't think of that.

Agree - That's how I built mine...

[LilRichard]

MM:  Doesn't matter if your floor is sealed if scuppers are under water and they fail.  they let in more and more water, and sooner or later the boat is swamped... even if the bilge is bone dry.

I have to ask- have you ever seen this happen?  My thinking is the only way this could happen is either your entire floor deck is below the waterline, or the incoming water would have to travel uphill.

That's exactly the problem, many of our boats have the floor at or barely above the waterline (hence, the scuppers are below), and as water comes in it fills the rear, lowering the boat more... and on and on.  Not to mention that ANY thruhull below waterline should ALWAYS have a valve on it.

I have not personally seen a boat sink, but I have read about them going down for this reason on Classic Mako.

If you feel comfortable leaving your boat in the water with scuppers under (and no failsafe like a seacock, plug, etc), that's fine... I never would.

[gran398]

MM:  Doesn't matter if your floor is sealed if scuppers are under water and they fail.  they let in more and more water, and sooner or later the boat is swamped... even if the bilge is bone dry.

I have to ask- have you ever seen this happen?  My thinking is the only way this could happen is either your entire floor deck is below the waterline, or the incoming water would have to travel uphill.

That's exactly the problem, many of our boats have the floor at or barely above the waterline (hence, the scuppers are below), and as water comes in it fills the rear, lowering the boat more... and on and on.  Not to mention that ANY thruhull below waterline should ALWAYS have a valve on it.

I have not personally seen a boat sink, but I have read about them going down for this reason on Classic Mako.

If you feel comfortable leaving your boat in the water with scuppers under (and no failsafe like a seacock, plug, etc), that's fine... I never would.

I see both points. But taking it a step furthur:

Most boats sink at the dock due to torrential rain. Hatches leak, batts run down, or the float switch gets hung up, killing the batts. Dead batts, hull fills. At that point, with water on the deck, the scuppers allow seawater in, finishing the job.

There is no practical way to install/use a seacock on an internal scupper drain, unless you were to cut an inspection hatch in the sole at both sides of the transom. Most of our boats do not have access through the bilge to get your hand in to manipulate a seacock mounted in this position (beneath the sole in the corners). No builder that I'm aware of installs such a system.

Point being, its not the closed system scuppers that sink boats. There is water in those hoses anytime the boat is in the water. What sinks them is as described above. Deck flooding via the scuppers is the very last step.

[MarshMarlowe196]

MM:  Doesn't matter if your floor is sealed if scuppers are under water and they fail.  they let in more and more water, and sooner or later the boat is swamped... even if the bilge is bone dry.

I have to ask- have you ever seen this happen?  My thinking is the only way this could happen is either your entire floor deck is below the waterline, or the incoming water would have to travel uphill.

That's exactly the problem, many of our boats have the floor at or barely above the waterline (hence, the scuppers are below), and as water comes in it fills the rear, lowering the boat more... and on and on.  Not to mention that ANY thruhull below waterline should ALWAYS have a valve on it.

I have not personally seen a boat sink, but I have read about them going down for this reason on Classic Mako.

If you feel comfortable leaving your boat in the water with scuppers under (and no failsafe like a seacock, plug, etc), that's fine... I never would.

That makes sense.  

But I tend to disagree that our Floor Decks, in their entirety, are at the waterline.  I believe that, with a heavier outboard, only the aft most portion of our floor is at or below the waterline.  Now, I've never measured the height of my floor in relation to the waterline (a task like that without skewed results would be difficult), but I can assume that my deck is above the waterline, at least most of it is.  I can assume this because the waterline is in fact level, at least at the medium of the average crest and trough.  So- if the waterline is level, and my deck is in fact level with it, when I pour a bucket of water on the bow to clean off castnet debris, the water would pool in the floor.  But this doesn't happen.  The water rushes to the stern, following the apparent downward slope of my deck.  That makes me believe that my deck is in fact mostly above the waterline.  If my deck was below the waterline, when I pulled the self bailing drainplugs/scuppers/etc, the water would rush in and fill all the way to the forward deck- but this also doesn't happen.  It fills to a point, with some apparent speed, then slows to a stop.  This point that it stops is where I assume the waterline is.

Take Skoot's boat- a boat designed to be self bailing with the anticipated weight of the outboards at the time.  Skoot has a 3-cylinder 2 stroke outboard, and his boat self-bails with the best of them.  Take that same boat, and put a 4 cylinder overweight 4 stroke outboard on it, and it's no longer self bailing, with the scuppers well below the waterline.  But this still doesn't sink the boat, it just annoyingly puts water on the floor at the stern.  I know from experience because I used to have the same outboard on my boat that Skoot does (same boat too), and the self-bailing feature worked great.  

BUT- even with that old setup, when I walked my 200lb a$$ to the stern, water came in.  When I walked back up toward the bow, it drained right out.  If the floor was level with the waterline, the water that made its way through the scuppers would have walked right with me to the bow.  It didn't.

More of the weight being at the stern of the boat is what's creating the slight downward slope in the floor, which is typical of almost every boat.

Some lamen's illustrations:





The angle might be a little exaggerated, but you get the idea.

I agree with you on a point-  any thruhull below the waterline should be sealed.  But to say self bailing scuppers can sink a boat whose floor is mostly above the waterline, and sealed from the bilge singlehandedly - I respectfully disagree.

[LilRichard]

I pretty much consider this guy the expert of all things boat design related:

http://www.yachtsurvey.com/sinking.htm

"To check if your cockpit scuppers are safe, first measure the height above the normal water line with tanks full. Subtract 2" if they're near empty. If the height above water is less than 4" you've got a problem. Get three 150 lb. or more persons to stand in one aft corner. Does the cockpit begin to flood with water? If so, your boat is in danger of sinking and you should consider sealing up the scuppers and improving the bilge pump capacity if necessary. "

[fitz73222]

Thank you! Now lets move on...

[MarshMarlowe196]

I pretty much consider this guy the expert of all things boat design related:

http://www.yachtsurvey.com/sinking.htm

"To check if your cockpit scuppers are safe, first measure the height above the normal water line with tanks full. Subtract 2" if they're near empty. If the height above water is less than 4" you've got a problem. Get three 150 lb. or more persons to stand in one aft corner. Does the cockpit begin to flood with water? If so, your boat is in danger of sinking and you should consider sealing up the scuppers and improving the bilge pump capacity if necessary. "

Well that pretty much makes the majority of all self-bailing boats in danger of sinking.  I guess seeing is believing.

Thank you! Now lets move on...

I digress.

[Skoot]

Well that pretty much makes the majority of all self-bailing boats in danger of sinking. I guess seeing is believing.

I couldn't agree more
MM. I think Your Illustration summed it up perfectly.  Water will simply displace itself when on the deck.  Whether underwater or not.

Pascoe talking about water on the deck entering the bilge area though leaky hatches, then your bilge pump failing. Well yea, then you have a problem.  The same thing would happen if a thru-hull fitting were leaking and your bilge pump/battery were dead. Our boats were designed with a self bailing deck, not a self bailing hull/bilge.

Lets say you plug all scuppers as Pascoe suggests, Then in the middle of the night a strong Florida storm rolls through dumping rain @ 2-4in per hour and continues through the night. Your deck starts filling with water and has no where to go. The water finds its way to the bilge through leaky hatches. The bilge pump attempts to do its job, but is weak and filled with dirt and debris.  Finally your battery fails and water continues to fill the bilge and your boat sinks.  Then the next morning you see your boat and say, Dammit I should have left the suppers the way they were, My old girl is 35+ years old and has not sunk yet.  Priceless.      Well just a thought anyway!

If anything I say leave her as is and follow fitz advise by raising the 2 outer drains, leave the center one as is and install a ball scupper in that one only. I put a ball scupper on both outer drains and pluged the center one.  Kinda the same idea

[gran398]

Thanks all....great discussion.

Began this thread hoping the recent 70's rebuilders (last 2 years) would offer their observations, input, and advice.

Just checked back through the applicable rebuild posts....when you're name is called, would you please step forward? ...

Capt. Matt, dirtwheels, puttz, KING CRAB, and fishskinner.

All of you guys did pretty work. Know most raised the cockpit sole height. Again, going back....by how much did you raise, were you pleased....and if you had to do it again, what change(s) would you make?

Guys, thinking ahead....we have living history here. Ten, twenty years from now, someone will reference our present posts. Lets do right by them, and go the extra mile.

Thanks for your input.

[Capt Matt]

Just my 2 cents
I raised the deck on my flatback roughly 4 inches, I don't see low freeboard at the stern of the boat as a problem more as a asset.
 I'm used to fishing out of a flats boat with a self draining hull with only foot high gunnels.  In big following sea's running too fast I have filled the cockpit a few times on my actioncraft by taking a wave over the bow or stuffing the bow into the next wave. The water drains out within a minute or two.
The high deck/low freeboard in the stern of my flatback will also make it much easier to throw a 12ft cast net of the stern of the boat. I should be able to even step up and stand on the stern cap to throw my net.
I made the cockpit drains go out the gunnels right up against the cabinet wall and will put  clam shell covers over the outside of them so water does not come in when I'm running between big swells. The drains I made large enough I can rinse grass out and small enough I can plug them if I'm ever really loaded down.
Alot of the commercial guys building boats out here on Pine Island make there cockpit drains the size of a tennis ball so if they are loaded with a few thousand pounds of mullet or 100 plus stone crab pots they simply push the tennis balls in the cockpit drains
I think ball scuppers below the waterline are a quick fix for a boat that sits too low. All it takes is a barnicale or leaf in the ball scupper and it won't seal right.
Nothing is worse than hearing the bilge pump kinking on all day long because water on the deck is leaking into the bilge. No Matter how well you seal your cockpit hatches water on the deck will get in the bilge
Capt Matt

[gran398]

Matt, thanks for your witness.

Exactly what we're looking for: usage, need, and real-world situation.

Like the idea of throwing a 12 foot cast net from the stern unencumbered.

Just depends on job description.

Thanks Matt...