6 Volt Bilge Blower

[maritimeclassics]

I feel it is one of the most important practices we can have and I know my family has been doing it for years. My Grandfather Jack Green was the first one to show me the ropes; he always lifted the hatches and checked the oil then kept them open until the engine was started. I can recall one story: he was boating the day before and didn’t realize that the oil was slowly draining out of the engine, went to start it the next time without any oil in the engine. I cannot recall if anything has been written in any of the old Chris Craft manuals or not but it would be fun for someone to research. Another question is how important are the metal down spouts that come from under the deck scoops and go close to the bottom of the bilge? It seems to me that they would not just be there to give air to the motor or to keep water from coming into the engine compartment, any thoughts?

[Al Benton]

Mike,

There was a fairly long discussion about these about 1 + years ago. It's in Hardware & Rigging called "Tubing - Vent Bilge" with the last post on Jan. 1, 2008.

Al

[maritimeclassics]

Al, I just got done reading the thread you suggested and now remember that great discussion we had. I didn’t think it covered the fumes in the bilge and should have known with the talent out there that it was very well explained. Maybe the fumes are getting to me, or it could be age.

[steve bunda]

Hi to all, have never used a blower in my runabouts,I have allways opened hatches after running untill engine is cool, and have open hatches for start up. One concern I have is when some people add more flooring in the engine compartment for additional storage, thus trapping fumes underneth.In a utility I can see the need to vent with a blower as it is sometimes hard to lift and prop up the dog house. Also the southern states have warmer weather than northern wis, So a blower is a great idea in all boats. I digress with a question, How many boaters know one should take a slow down pass before shutting the engine down after a good hard run? steve

[Al Benton]

Steve, when I first got the cruiser (7-8 years ago) my son-in-law pointed that out to me. He told me the temp. gauge will practically peg if you don't let the water pump cool things down before she's shut off after a hard workout. Good advice.

Mike, does either of your post-war runabouts have original vent tubes? Do you have any photos?

Al

[NSJA]

Wow,

This is a great discussion. I am learning a lot from all of you experts. Joining this club has certainly been a pleasure for me.

It seems that most runnabout owners do not use blowers, but, after seeing the article in the latest issue of Rudder, I thought that it might be worthwhile...

NSJA

[maritimeclassics]

The 20' Custom came with 2 out of the 4 and the 17' Deluxe came with two, I cannot be sure how many the Deluxe is suppose to have. In the 20' Custom the 2 aft downspouts closest to the fuel tank were missing but the holes for the small nails are still visible in the deck and also the screw holes to the bottom frames are present. I do not have pictures of under the decks of the Deluxe with me as the boat is in Oregon waiting for me to get back and finish it.

[Al Benton]

Mike, Thanks for the photos.

These appear to have been factory painted. It's a question that's still up for grabs whether they were bare or painted on post-war ones.

Al

[maritimeclassics]

I have seen them both ways, but I have seen alot more painted. They seem to stick out if they are not so I always paint them(post war). I know on the 20' Custom that we have in the shop now they were painted.

[rdapron]

Mike, your custom should also have a tube in the bow from the forward deck vent along with the aft vents you mention.

rob

[Brian Robinson]

Good addition Rob - I have seen some (20' Customs)that used the ventilating bow light hole instead to mount the vent tube originally, which makes sense to avoid the whole dash shifter controls mess right underneath the bow deck vent. I think this is the way the one Mike is working on came.

[Charles Wilson]

Hello all-

Might the "O'Malley Spec Sheet" for those boats that have them reveal the number, length, dia., Etc. of the vent pipes?

Just a guess on my part but it's logical that the pipes would at least be used on the forward intake scoops to create and carry a positive pressure low in the bilge where the fumes settle and maybe not used on the aft exhaust vents, allowing the fumed air to vent everywhere? On the cruisers/enclosed boats perhaps aft vent pipes were used to get fumes out of the contained space? Hence- what does your O'Malley spec sheet indicate, maybe therein lies the answer for our different boats.

I would also guess that this was a thought out and "engineered issue" to maximize venting- but maybe only after some "unfortunate events", then promoting changes maybe even during a production run?

Regarding were they painted on not, during the building sequence, were/are they sleaved or fastener connected to the plated air scoop and then inserted through the deck after varnish and interior hull painting- which might explain no paint. Were the interiors painted with a brush and then in some later year or at some plant, spray painted which might explain the painted ones? When I do refinnish my interior of a 1949 Special Runabout am I spraying or brushing?

[Al Benton]

Charles, I kind of remember a discussion some time ago about these spec. (or build) sheets not being continued after WWII. I don't remember what they were called or where to find the topic that contained that subject.

My '48 17' Deluxe has 4 vent ducts that appear to be original. Unfortunately, the photos are lost in a hard drive that no longer is accessible and the ducts were removed for total restoration.

Back to the topic subject. I think the best location to add a bilge blower on mine would be on one of the aft vents that faces aft. They're smaller than the forward ones though but those face forward. Question: Does air flow freely through one of these blowers when it's not running? If not, would having the blower add too much restriction to air flow while under way? If so, the blower could be kept running, I suppose. Am I a worry-wart or what?

The air flow pattern on the Cobras is backward, the forward vents (on the fiberglass engine hatch) face aft and the aft vents face forward. I wonder what that's about.

Al

[steve bunda]

Hi to all, this string is opening up some good brain storming. My last post asked the question about a slow down cruise after a hard run. the answer is correct on the proper cooling of the engine before shutting down. A few more points,a slow period of operation before shut down will vent engine fumes,and cool engine temp. Sometimes engines shut down hot for a few minutes and then restarted will allow cool northern lake water enter a hot block and cause cracks. back to venting , I suppose the enginners at Chris Craft were allways improving and changing the vents based on boat designs. I will post the venting factory work on a continnental I have in the shop .On many boats on would assume the air intake is in the bow and exhaust in the stern. This begs another question, On the 19 foot barrel back why did the factory install 1 1/2 inch thick floor blocks under the second seat to block the air flow? steve

[Don Vogt]

well, as Al says at the end of the first page of this thread, some do and some don't open the hatch before starting, but I think it is only prudent to do so. If there is any gas leaking, odds are you might smell it with it open; and in any event, less likely to blow the boat up.

[Al Benton]

Steve, was the "Isolating bulkhead at amidship seat-back" added as a relult of Memo #771?

Memo #771:
19’ Runabout-Isolating bulkhead at amidship seat-back
2-Pat. 2534 ventilators just aft of amid ship seat back-facing forward.
Opening 7 sq. in. minimum.

2-Pat. 2534 ventilators on stern deck just forward of gas tank facing aft.

My guess is the bulkhead allowed the engine compartment to pressurize, forcing engine fumes out through the added aft vents in lieu of under the aft seat and into the cockpit.

Al

[NSJA]

Hi Don,

I'm glad that you joined this discussion. Do you have a bilge blower on Jenny II, and if so, what is the configuration and what are the specs of the blower? I know that your 17' Deluxe only has 2 deck vents instead of 4, so even less passive ventilation than mine...

NSJA

[Charles Wilson]

Hello-

The good message in this subject is all of us are learning about the Omara spec. sheets (hardware records of each boat). I was incorrect in calling them "O'malley", it's Omara.

Al- The location of the Omara thread is under Hardware and Rigging, pg.4, "Bumper Cleats", Charles Wilson, Dec.30 2006. Then see Bill Baslers post of Oct.10,06. Your questions about air flow are good ones as you want to improve what is there not mess it up.

This dialogue states that only for some production years have these records been found and that they reside with the Mariners Museum. If they were available for my boat, I'd have mine. Like the "Boat Equipment Record" there is/was one for each indivigual boat. Bill Basler knows a lot about them. Their existance/content would be a good subject for a Brass Bell article.

Regarding vent pipes, I bet they were "engineered" for max flow (gas fume venting, engine cooling and aspiration) and that would be different for each model boat. Obviously, if you don't have a blower and your boat is NOT UNDERWAY, there is NO ventilation. Starting an engine in a cold start choked is the time you are introducing the highest risk of flooding the carb and or a backfire. When you most need it there is no venting until you are underway! As the explosions went off it became more of an issue and the Coast Guard eventually interceeded with regs. This is why we should pay more attention to the potential, ie., many of our boats would not come even close to today's saftey standards. We are very vunerable and this is a serious subject with potentially dire outcome.

Gas is really bad stuff. Especially on old boats before stds.!

I believe that air flow and circulation is/was initially designed and engineered as a somewhat "balanced system" and if you don't put it back together as one (or better) you are taking additional risk to something that's already too big. Al- I have no idea about the Cobra "system" and it does sound odd. Inlet pressure and equal out let or maybe even a suction coefficient may have been considered amoung other things. Maybe one of our older members or C-C employees can shed some light on the sophistication level taken in design and mitigated redesign as events happened. To those of you who were not around then, explosions and fires were not uncommon. (On the Runabouts, think about where your origional fire extinguisher is- on the carb side, about a foot from the carb. You will never get to it). I can emagine how over the years our prior owners pulled out these old bent up vent pipes that didn't seem to do anything but get in the way!

In the fall and spring my dad use to store his beer next to the forward inlet pipe and some times if she was leaking, in the bilge water was just fine.

[steve bunda]

To Al, and all interested, I am aware of the Chris Craft memos , and the prewar 2 vent verses 4 vents for engine compartment evacuation of gases. My observations comments and thoughts are base on boats that I have in my shop currently ,and past projects. Some things Chris Craft did make sense and other times I wonder what they were thinking.I suppose the normal was change, base on the particular design, enginnering ,production, regulations, and marketing. sincerly, steve

[Don Vogt]

Thanks, no I dont have one but probably would install one if I found a good 6 volt arrangement. There is another thread that occurred about 6 months ago or so in the buzz about 2 vents or 4 vents. I think it was around mid 1941 that the coast guard required 4 vents on all these boats and prohibited the old "bottom feed" gas tanks like the one that came in my boat. Even though my original tank was in fine condition, we replaced it with a top feeding stainless steel tank made to match. Never want a leak and 30 gallons of gas in the bilge. That was one of the few changes from originality that I was willing to make. I think where safety is concerned, orginality should always take a back seat.

BTW, how are you coming on your boat?

[NSJA]

Hi Don,

So far, the options for a 6V blower are:

1. Find a used one on e-bay or elsewhere; I was able to purchase one from a club member.

2. Use a modern 12V blower (available at West Marine, Classic Boat Connection etc.)and run it at lower capacity, using your 6V battery.

3. Same as option #2, but use a voltage doubler: www.theledlight.com/misc-controls.html

4. Use a modern 6V blower: www.suttonblowers.com/mselect.htm
These are pricey at $330 + shipping. I have not yet verified whether or not they are USCG etc. approved.

I have not yet decided which direction to move forward on this, but, I have decided to install some type of active ventilation system.

I am currently working on fixing a small gouge in the hull below waterline and re-painting the bilge. Otherwise, I am ready for the maiden voyage!

Best,

NSJA

[rdapron]

Memo #771:
19’ Runabout-Isolating bulkhead at amidship seat-back
2-Pat. 2534 ventilators just aft of amid ship seat back-facing forward.
Opening 7 sq. in. minimum.

My guess is the bulkhead allowed the engine compartment to pressurize, forcing engine fumes out through the added aft vents in lieu of under the aft seat and into the cockpit.

Al, your guess confirms my observations. I have been in several post war boats that have had new bottoms and had the bulkheads omitted. It seems that some people choose to not replace these bulkheads when putting in a new bottom. I suspect that the bulkheads were soft due to the proximity of the bilge water, and in many instances the use of poor materials hastened their demise. Regardless, in all cases fumes from the engine could be detected, specifically crankcase fumes.
rob

[Al Benton]

Don, it was the Memo (#771) that I partially quoted earlier that added the other 2 vents. I believe the memo was dated 1/6/41 so runabouts prior to the memo had 2 vents. I believe the memo includes hull numbers of the first 1941 models that received the change.

Steve, the above mentioned memo includes the note regarding the 19' Custom bulkhead at the rear seat-back being isolated but have to wonder why the other models didn't include the same note. The "1-1/2" floor blocks under the second seat to block the air flow" you mention must be due to this memo. My guess as to why they were added seems logical but, on the other hand, why did it apply only to the 19' model? Was it ok for 17' Deluxe owners to smell fumes in the back seat but not 19' Custom owners? Who knows?

Charles, how could I forget about that fun thread? I believe it was your first post on Boat Buzz. It's hard to realize that was over two years ago now. Bill Basler building our hopes regarding the O'Mara build sheets and Brian Robinson popping our balloon just minutes later. The "bumper" vs "fender" cleats was fun and informative.

Adding bilge blowers to some of these, especially pre-memo #771 ones with only 2 vents, would be a problem considering there's no exit vents, only supply ones. The only exit means was probably under the aft cockpit seat or any gaps in the engine hatch. The solution may be to "supply" air with a blower through one of the two existing intake vents. It would exhaust where ever it did before.

The bottom line is to "Check for gas fumes" every time. The action of lifting the hatch should be routine, not just for checking the oil but for every time you start her up, bilge blower or not.

Al

[Brian Robinson]

I think this thread has branched into several things. There are three separate issues here (aside from the initial 6V blower topic).

The sound insulating bulkhead, keelson stiffeners (1 1/4" blocks under the second seat), and the isolating bulkhead were three separate engineering issues dealt with between 1938 and 1941. First was the 1/2" Firtex Sound Insulating Bulkhead added to the seatback forward of the motor in all runabouts and utilities except the 15.5' models. This was memo #493, dated 7/15/38 and began affecting the following 1939 model hulls:

16' Race #42110
17' R/A #71403
19' R/A #48500
19' Sportsman #19558 (there is a typo here on the actual memo saying #19958 which never existed)
22' R/A #22114
25' R/A #25074
27' R/A #27046

The second issue was the keelson stiffeners, made of 1 1/4" thick Philippine mahogany on the 19' runabouts and Sportsman's on frames #4,#5,#6 (plus #7 on the runabouts). This was memo #547 dated 12/5/38 and began affecting hull#s 48548 and 19558.

Lastly is memo #771 which Al describes. This indicated the switch (among other things) to the Isolating Bulkhead which was a somewhat complex constructed part in itself - there are line drawings dedicated to this. It sealed off the area below the tops of the stringers, yet had its own venting holes built in where the engineers at C-C wanted them. This began affecting the following hull numbers for 27 different runabouts, utilities, and cruisers: 52623, 57174, 71769, 48837, 22206, 27060, 42503, 58084, 81198, 22684, 12520, 24941, 29458, 66000, 51146, 92093, 34060, 54132, 64048, 29448, 56048, 33738, 3718, 59016, 44008, 8416, and 5507.

Hope this helps any confusion.

[Al Benton]

Brian,

Generaly speaking, pulling bits of information out of context ends up being miss-leading. I'm quite guilty of doing just that in this instance. I included parts of an excerpt that Bill Basler included in his post dated Oct, 31, 2007 regarding the vents and tubing.

It included a line item adding the blocking under the 19' Custom seats and I related it directly to the subject of ventilation changes mandated by the USCG. Other lines on the Engineering Change (memo) included adding the vents and ducts. So the blocking was more of a sound insulation issue than having to do with engine room ventilation.

Thanks,

Al
Lift & Snuff!

[Don Vogt]

we should resurrect this thread in light of the accident in georgia and the discussion on Woody Boater. I am wondering if anyone has a current suggestion as to 6 volt bildge blowers?

[bjornbakken]

Since 6V blowers are harder to get than a kidney transplant, I am trying to find a repair shop for small electric motors to restore mine. I have a 6V Italian made bilge blower for a Riva Florida that took a dive, and the motor is seized up. Can anyone offer a recommendation?

[evansjw44]

Siezed is more mechanical than electrical. Any good starter/alternator shop should be able to free it up without ever worrying about whetner it is 6 volt ot 12 volt. You can probably free it up yourself with a little patience and some penetrating oil. It might need some new bearing as corrosion might be the cuplret here.

[tkhersom]

we should resurrect this thread in light of the accident in georgia and the discussion on Woody Boater. I am wondering if anyone has a current suggestion as to 6 volt bildge blowers?

Thanks for bringing this thread back to life!

It was a great read and went all over the place.

Does not sound like 6V blowers are readily available, may be time to modify to a 12V system.

[Don Vogt]

you're welecome, tk, however, i am not sure you want to do that. Being somewhat of a purist, i am staying 6 volt although it is a pain sometimes, i agree. I think by taking certain precautions such as checking your fuel lines from time to time, always opening the hatch and sniffing before starting, etc. one can manage without a bilge blower. However, a 6 volt one would be nice if we could find it.