side vents for and aft on hull
 

What purpose do these vents serve ? I have a 76 ob 23 cc the front vents are turned foward like an air scoop, nice in the hot summer but bad when sea duck hunting in winter.
I am trying to be convinced to remove them both during restoration for astetic reasons.

Any facts or opinions would be helpful

thanks, G.

Do you like a bilge full of mold and mildew? If not, leave those vents alone!

Like Denny said, leave them alone. They let air circulate between the hull and the floor. They help save your floor. My floor is original (35+ years old) and completely solid. My boat is an outboard too.

Yes, the front vents face FORWARD, as you have them now. They also should have a aluminum splash guard frame around them....see below. I've never had a water entrant problem.

Jim

thanks for the info guys, the vents stay. I do not have the splash guards as seen in your picture. Do you think they make a difference ? This boat had big mahogany sprayrails on it that I just removed, so they probably defered water away from the vent.

Yes, I believe they do make a difference. They were std OEM in 1977. I'm sure you can find some. Try a "WTB" post in the "For sale" section. I'm sure someone who mistakenly took out/off the vents on their boat would be willing to sell them to you cheap. Probably a few sets just laying around.

I re-installed mine 2 years ago with new white ones from West Marine. I would really like someone here to make/offer some SS or aluminum outer frames :) Sure would save on the fender damage to the vents.

I don't think it's a big deal if you remove them. No other boat has vents like that, even the newer Seacrafts don't have them. I have never heard anyone complain of mold or mildew. Does it make the brand more unique? Yeah, but I personally don't like the vents in the bow.

Turn the forward vents around, no water will get in and you will still have good ventilation for your bilge. If you restore it I would take them out. I used to take on water thru the rear ones on crappy days drift fishing with guys jigging on one side of boat. This was on an inboard 23. I had good venting thru my console and that helped. Also the docks would bang them up or a buddy would tie up to you and bust the plastic ones.

Selfishly, I'd like to see one of you fellas glass them shut and then cut some slits back in so they are a flush, functional, and part of the hull. I think it would look traditional but new. I'm sure they do help to some degree, how necessary, who knows? It kinda reminds me of a old Monterey and Jim Smith's salon vents, in the hot SoFla sun they definitely felt slightly cooler and less stuffy than some other similar boats.

Bilges are vented for a number of good reasons. Learn from others.

When form over takes function, performance looses.

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??

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.

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.

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.

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

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!

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

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 :rolleyes:

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 !

[QUOTE=BigLew;212233]I guess Istarted a fire storm

You didn't start a fire storm at all I'm new to SC, been a long time mako guy just stepped into my dream machine. ;) and want to be sure I don't kill anyone or my boat! I appreciate all this knowledge

No vents = Death & eminent destruction, vents = bliss & immortal SeaCrafting, lol. For myself I understand why they are there I also think they can sometimes look out of place and more dated than classic. One person's choice isn't another's, to each their own.

Capt Chuck,
I have a 1978 23' that is in need of new vents. Where did you get yours?

Thanks,
Mike

There are plenty of 20 seacrafts with below deck tanks and no vents. Were the 20s originally built having the vents?

Let the imagineering commence. I would have to take some numbers with a tape and think for a while. Boat owners warehouse has a few designs that could be improved quite a bit. I`m thinking sleek, subtle, and low profile. Match the gelcoat? What are your plans for the old spray rails?

Cheers and keep asking,
GFS

mine has vents

Of all the 20s on the pictures portion of this site, I don't think any have vents. Whats the big difference between the 20s and 23s???

Interesting. I never noticed that the Potter era 20s don't have vents. My 20 is a Seacraft Industries Hull, and like Mikem's it has vents.
Dave

Mine has vents, big clamshell type made from Marinium on aft gunnel; stbd side faces forward, port side faces aft, with hoses leading down into the bilge. The later 20's had plastic vents in hull just forward of transom, similar to the 23's. The later I/O models, like Strick's 20' Sceptre had vents just aft of the engine box.

Hey all listen Im not trying to be difficult or stubburn here just want as much info as possible thx for the prior posts. I appreciate it.
The queation waa posed why dont 20s have them???? Again my wheels start, i call some of my marine guys all with different answers.
Is it just as simple as obviously SeaCraft made the Inboard model on the 23, could it be that they just kept the hull design for all 23s? So each hull is the same? I'm just throwing it out there, as a long time boater (well I'm only 32yo but been boating my whole life) I completely understand the air vents on an inboard, dangerous situation there, I have seen that explosion as I'm sure a good amount know ir heard of a boat blowing apart bc the blowers weren't put on.
But the outboard is set back 3ft (with bracket) so fuel line is out in the open air for sure. As far as the tank and fumes,...I just don't see why it's different from any other boat? Whether Foamed tank or not, idk? Just seems like u would see it more on other boats wouldn't u? I mean a fuel tank under he console is not irregular, the hook up and sender are located there and I assume fuel fumes would be the same issue on every similar hull? No? Again even the 20? Why wouldn't hat be an issue in that model?
Are there any cases of SeaCrafts blowing up for this reason? I don't know...... im I asking...?? i cAn do a search. I'm not talking about other model boats, again I have seen that happen. Im Talking SeaCraft 23s and something ill happened from lack of vents. As opposed to some drunk dude who ignited a flare while filling gas lmao!!! Again I'm just curious it's and interesting topic and I want to be sure I want/need to do this before I redo the precious owners fill job.

Sully

Ok, so the question is; why have bilge vents on an outboard boat?

As Denny (Bushwacker) and Jim (77SceptreOB) mentioned early in the thread, bilge vents allow air to circulate in the bilge to keep moisture levels down. A sealed bilge with even a small amount of water in it is going to create a mini diurnal water cycle. During the day, the hull will heat up and water in the bilge will evaporate. At night, when the hull cools down, the humidity will condense on the inner surface of the hull and the underside of the deck. Polyester based fiberglass is not waterproof. Constant or frequent exposure to liquid water is going to cause it to soak up moisture I can't see that being good for the wood core in the decks and transoms of these boats.

In a vented bilge, humid air will be replaced with outside air. The air in the bilge is more likely to be close in temperature to the hull, which should reduce condensation in the bilge. The safety concern over fuel spilled in the bilge has already been discussed. To me it's a lesser issue in an outboard boat. All electrical equipment in your bilge should be labeled "ignition protected" anyway.

To me, the reasons for having the vents outweigh the aesthetic considerations. Personally, I like the look. It says "function" in a world where we've sometimes lost track of the reasons we do things.

Dave

well, i have a '77 and the deck is still solid as a rock and im guessing thats primarily due to the ventilation in the hull. havent seen alot of other boats of its age that i can say last as long

It still begs the question, why didn't the 20s at least Center consoles have vents like their big brothers? I have small circular vents inside the boat on the sides but I haven't seen a 20 with the exterior vents. Just curious...

I hear ya bro! Idk? Again the 20s didn't have an inboard model no vents, the 23s had all 3 (I/O, OB, IB) I wonder if they were made for ventalation on the IB models but just kept the same hull design to make production easier across the board? Idk I'm just guessing.
Everyone has their own opinion on it which is interesting to me. I'm dropping the boat off for paint now ill decide down the road. Idk what imma do with mine yet. Now I'm up in the air about it.

A bunch of you guys make some great points imho. Many things mentioned are simple easy concepts that are known by many and I would think and hope are taken into account by most people with an opinion. There's no way to argue against the multiple reasons of there being some benefit to any confined space being able to exchange air let alone in mostly inaccesable bilges and netherregions of most small old polyester boats. Many of which are surrounded by water constantly and some, right or wrong, leak every rain or worse. Not to mention, boats in areas where freezing and expansion can be issues on top of common osmosis, delamination, moisture and rot. Though, I personally do believe it is possible to speculate to the degree it's needed assuming the boat's bilge isn't normally inundated with moisture and the fuel system as a whole is up to snuff, tank and other spaces foamed or not. It's one thing to fear explosion than to respect it and understand what limits it's possibility and the things that have to be 100% to ensure that doesn't happen. If the debate leans more to how the hull vents and lack of the foamed tank and such are more forgiving as the boats slips away from being 100% and into the aging process of "that broke loose", "this crack here", that leak there" then I'd agree though I've seen plenty of trashed SC's too but there tends to be less to get trashed compared to some other boats. Whether or not a fuel tank leaks in 20-30-40 years isn't a big thing to me so personally that's not a concern for me. I also think some people really took care of some of these well built boats and someone definitely can't deny there are a fair amount of fairly original 20-30-40+yo hulls out there. As fun as it is to keep seeing how long you can go on the original floor and transom at some point it's probably gonna need to be done for the majority of people no matter what precautions have been taken or are designed into a boat short of epoxy or vinylester etc. I also think many are rehabbed for multiple reasons using newer, better products that vented or not the hull could go a lifetime without a major rehab if done correctly and sometimes incorrectly even, depending on different variables. Also, when you start to bring up i/b's, i/0's , cabins, fabrics, carpet etc. that brings up other things that can surely be talked about but are also well known.

As far as 20's, early 20sf's had fuel above deck, could that be why there's no vent on those? As stated some later ones have vents, could it be because of fuel below deck? Could it have been because of the desire to just make one hull for multiple models as stated? Could it have been for aesthetics? Could it of just been a change in thought? What about the tweener Potter years that have fuel below and no vent? As stated, I/0 20's had transom vents/ blower for other obvious reasons. My personal feeling is the gunnel rod storage holes especially on the 20's that have the larger cutout in the bow provided some level of ventilation. I also think about how small a 20 is and maybe someone thought a hull vent(s) would do more harm than good or be moot if running through some rough stuff. If I wanted to play devil's advocate to some degree then I would have to ask; If there was such a huge concern and foresight to the moisture end of the of it, then why have uncapped rodholders, why have a lower than deck height bow compartment with a weephole going to the bilge, why have a in deck baitwell/storage that drains into the bilge? As far as fuel vapor, why would there ever have been fuel below deck, why wouldn't every boat have a bilge blower(s)? I think the biggest reasons are probably simple, maybe because everything is a tradeoff but worth the tradeoff within a percieved acceptable margin of safety, durability, reliability, convenience and performance in pursuit of having the least amount of unuseable room, a lower center of gravity and slightly to much larger fuel capacity.

Wasn't Mr. Potter on here not to long ago, maybe he can share his thoughts on his era boats?

All I know is; Vents, no Vents as long as your boat's not taking on water and you don't have any apparent exposed ignition sources or a fuel smell I am more than willing to stare at and appreciate any of your SC's and let any of you take me out on them too, lol.

In a 23 inboard it makes perfect sense. They are the engine intakes. That is how the engine breathes. I would also bet at least one of those vents, probably one of the stern vents has a hose going down into the bilge below the engine oil pan and it's attached to a blower. I am reasonably certain that is why they are on the 20 and 23 IO's. Just adding the vents isn't anywhere near adequate to vent a hull from fuel vapor with out a blower. Especially when it matters. AT START UP after a boat has been sitting and the vapors have had time to accumlate. The blowers are turned on for a few minutes before start up and turned off after the engines fire. Once the boat is underway all the airflow necessary to vent the hull is created through the engine intakes.

My guess is they are there because of the inboard models and they just kept the line looking the same across the board.

If you have an inboard boat move the vents to the Center Console or into your liner. It will accomplich the same task and your hull will look cleaner. I/O guys move them to the engine cover or the liner.

Vents
 

My 74 CC has the exterior vents (original)