side vents for and aft on hull - Page 2

Sullivan21 · #11 02-14-2013, 08:16 PM

Guys now Im nervous the guy I bought the boat from glass over the vents which I have to be honest I love, I'm not a fan of the vents I knw they are a "classic" SeaCraft trait but I'm not into them. That being said what will happen? Should I open them back up?
I don't see any other boats with them so I didn't think much of it. I do have the circular vents on each side. The SS ones about half way up the gunwale. Idk??

BigLew · #12 02-14-2013, 09:48 PM

Is your fuel tank below deck? If the answer is yes, VENTILATE the bilge.

I have seen first hand what fumes in the bilge can do. A 16 year old kid never saw it coming! The obituary was needless.

Sullivan21 · #13 02-14-2013, 10:24 PM

I'm just curious I have a Mako 211 with a below deck tank and there aren't any side vents, what is he difference? And BIG LEW what happened it exploded? Is it the same idea as putting blowers on before firing an inboard? I don't get it as it would seem fumigated. But I don't doubt y'all either.

Sullivan21 · #14 02-14-2013, 10:27 PM

Quote:

Originally Posted by Capt Chuck

You can cut the inner liner from the inside of the vent channel just align of the stepup platform and put some ventilation vents, then make sure you have some breathers aft.

BTW: Why do you all hate the look of the vents? I made some custom ones that are less than the rub rail and don't rub the dock. Use your imagination and keep the ventilation below the deck maintain the look of your SeaCraft or go buy a GD Contender or the like

Ok now that looks nice! Idk Capt. my eye seems to be drawn to the vents and they just seem unnatural as you don't seem them on similar "sleek" looking hulls, they kind of "break up" the paint for me. Just my opinion. Did you do the same of the forward one as well?
N I ain't getting a Contender or whatever over my SC!!! I love this rig. Again I'm not the one who covered them. I'm just asking.

Bushwacker · #15 02-14-2013, 10:47 PM

There is much more to the issue of bilge vents than just preventing mold and mildew, although I have seen the mold/mildew issue discussed here on boats where the vents had been closed up.

SeaCraft was always one of the rare builders, at least in the Moesly/Potter era, that did NOT foam in their fuel tanks, for good reason, AND they installed hatches over the tanks so you could remove and inspect them for leaks without cutting up the deck! If you read some of the brochures from the early 70's, Potter bragged about that, saying it was NOT a good idea to foam in fuel tanks because of the corrosion it caused, but said it cost them more because "THEN THEY HAD TO VENTILATE THE BILGE"! That sounds like this is a USCG requirement; does anyone know for sure? The Moesly boats all predated the USCG flotation requirements, so none of them was filled with foam to my knowledge, and they all had clam shell type vents on the gunnels and/or engine boxes, whether I/O or O/B versions.

The rationale for no vents on some boats MAY be that IF there is no empty space for fuel vapor to collect, (i.e., the entire bilge is full of foam) then there is minimal risk of an explosion, since there isn't any way for air to mix with the fuel vapor. It's the vapor that's explosive, and even then, there is a relatively narrow range of "fuel/air ratio" in which it will ignite. (We all know an old carb'd engine won't start if it's flooded by a choke that sticks closed, nor will it start when cold if the choke sticks open!) If the foam is saturated with liquid fuel, it could certainly burn if exposed to air, but I'm not sure there is enough air in a foam filled bilge to create an explosion hazard. Maybe some fire-fighter members of the forum who are more knowledgeable than I can provide more enlightenment on this subject and/or correct me if I'm wrong about this theory!

Now I'm not familiar with the 1980's and later SeaCrafts, and maybe they're full of foam, so that might explain why they don't have vents. But the bottom line is that I believe the Potter-era boats with open spaces around the fuel tank were intended to have ventilated bilges to eliminate any explosive mixtures, so I would not eliminate the vents on one of them, or ANY IB or I/O model with the open space around the engine for that matter. Granted, there are fewer ignition sources with an outboard, but what about bilge pumps and solenoids for power trim and trim tabs, etc.? Seems like anything we can do to reduce the risk of an explosion from even a small leak (I think the fumes from a cupfull of gas = 1 stick of dynamite!) is well worth doing, even if the probability of ignition is small. And if you have a large enough fuel leak, I suppose one could argue that ventilating the bilge might make it worse by just providing enough air to create an explosive mixture that would otherwise be too rich to ignite! However the human nose can supposedly smell an explosive mixture, so I would think anything too rich to ignite would be real obvious. I had a very small amount of seepage around the sending unit gasket one time, but the gas smell in the cabin of my Seafari was overpowering and I've been a fanatic about sealing that gasket ever since! For that reason, I guess any boat with an enclosed cabin like a Sceptre/Tsunami or Seafari should have hull vents, even if the bilge is full of foam. The Seafaris were only built by Moesly and Potter, but I think SeaCraft Industries built some Sceptre's in the 80's; don't know if they had vents or not, but I think they should have even if they're outboards! Denny

Sullivan21 · #16 02-14-2013, 11:38 PM

Quote:

Originally Posted by Bushwacker

There is much more to the issue of bilge vents than just preventing mold and mildew, although I have seen the mold/mildew issue discussed here on boats where the vents had been closed up.

SeaCraft was always one of the rare builders, at least in the Moesly/Potter era, that did NOT foam in their fuel tanks, for good reason, AND they installed hatches over the tanks so you could remove and inspect them for leaks without cutting up the deck! If you read some of the brochures from the early 70's, Potter bragged about that, saying it was NOT a good idea to foam in fuel tanks because of the corrosion it caused, but said it cost them more because "THEN THEY HAD TO VENTILATE THE BILGE"! That sounds like this is a USCG requirement; does anyone know for sure? The Moesly boats all predated the USCG flotation requirements, so none of them was filled with foam to my knowledge, and they all had clam shell type vents on the gunnels and/or engine boxes, whether I/O or O/B versions.

The rationale for no vents on some boats MAY be that IF there is no empty space for fuel vapor to collect, (i.e., the entire bilge is full of foam) then there is minimal risk of an explosion, since there isn't any way for air to mix with the fuel vapor. It's the vapor that's explosive, and even then, there is a relatively narrow range of "fuel/air ratio" in which it will ignite. (We all know an old carb'd engine won't start if it's flooded by a choke that sticks closed, nor will it start when cold if the choke sticks open!) If the foam is saturated with liquid fuel, it could certainly burn if exposed to air, but I'm not sure there is enough air in a foam filled bilge to create an explosion hazard. Maybe some fire-fighter members of the forum who are more knowledgeable than I can provide more enlightenment on this subject and/or correct me if I'm wrong about this theory!

Now I'm not familiar with the 1980's and later SeaCrafts, and maybe they're full of foam, so that might explain why they don't have vents. But the bottom line is that I believe the Potter-era boats with open spaces around the fuel tank were intended to have ventilated bilges to eliminate any explosive mixtures, so I would not eliminate the vents on one of them, or ANY IB or I/O model with the open space around the engine for that matter. Granted, there are fewer ignition sources with an outboard, but what about bilge pumps and solenoids for power trim and trim tabs, etc.? Seems like anything we can do to reduce the risk of an explosion from even a small leak (I think the fumes from a cupfull of gas = 1 stick of dynamite!) is well worth doing, even if the probability of ignition is small. And if you have a large enough fuel leak, I suppose one could argue that ventilating the bilge might make it worse by just providing enough air to create an explosive mixture that would otherwise be too rich to ignite! However the human nose can supposedly smell an explosive mixture, so I would think anything too rich to ignite would be real obvious. I had a very small amount of seepage around the sending unit gasket one time, but the gas smell in the cabin of my Seafari was overpowering and I've been a fanatic about sealing that gasket ever since! For that reason, I guess any boat with an enclosed cabin like a Sceptre/Tsunami or Seafari should have hull vents, even if the bilge is full of foam. The Seafaris were only built by Moesly and Potter, but I think SeaCraft Industries built some Sceptre's in the 80's; don't know if they had vents or not, but I think they should have even if they're outboards! Denny

Thanks for that reply that about says it all, um.....ok so I'll b putting back my VENTS!!!!!! Who am i to question the masters of the SC? They have been that way for 40 years I don't think imma mess with it!
Thx all

BigLew · #17 02-14-2013, 11:42 PM

I guess Istarted a firestorm- sorry!

I was on Lake Murray outside Columba, SC iin a sailboat, when I saw a 16 year old boy jump in a Donzi and turn the key. The boat blew up killing the boy. He hadn't turned on the bilge blower.

The vents are faced forward in the front and aft in the back for a reason. If the boat is on a mooring or at anchor or running, it generally faces into the wind. This way, the bilge is ventilated of fumes. Removing the vents reduce or eliminate the venting of the bilge, and thus any gas fumes. A bilge pump will take care of any water taken in through the vent or get another bilge pump! Your choice!!!!!!!!!!

When form takes priority over function, performance looses!

Sullivan21 · #18 02-15-2013, 12:06 AM

Quote:

Originally Posted by BigLew

I guess Istarted a firestorm- sorry!

When form takes priority over function, performance looses!

Well said I agree. Looks like another project to add oh well. For good reason.

Capt Chuck · #19 02-15-2013, 01:39 AM

Quote:

Did you do the same of the forward one as well?

Yes, The only water I get in the forward vents is when I squirt the mud dobbers nest out.... The water line when running is aft of these forward openings, If water is getting into them, you got a problem with forward weight, otherwise the seas are too rough and you should be home with the wife enjoying life not getting your ass beat to death

gchop · #20 02-15-2013, 10:18 AM

Well as expected alot of different opinions. I am not crazy about how they look but function is king. maybe a better mousetrap like custom cut flush vents made out of starboard. I have a cnc machine and have done alot of varied starboard custom parts
(babylonboatworks.com) if anyone has any design ideas im open to suggestions !