My 2003 Four Winns 285 Sundowner has no transom vents. There are two vents' one on each gunnel but both face fore. There are a pair of bilge blowers in the port tubes that draw air from the starboard vent and push air out, but again the vent faces forward. That is not an issue when idling but what happens at a 30 mph cruise? Four Winns says its not an issue but I equate it to trying to put 10 lbs. of crap into a five lb. bag. Shouldn't there be transom vents to effectively exhaust hot air and potential fumes while cruising? Am I making a mountain out of a molehill?
Four Winns transom ventilation
- Thread starter woodshoes
- Start date
The "vent" underway is through the exhaust. The engine is sucking large quantities of air and sending it out the exhaust. The vents are to provide that air and should face forward to provide better flow, like hood scoops on racecars face forward. The blowers are primarily for when the engine isn't running.
In round numbers to burn 10 gallons of fuel requires injestion of about 10,000 Cubic Feet of air.
In round numbers to burn 10 gallons of fuel requires injestion of about 10,000 Cubic Feet of air.
If that really is the case, it sounds like a poor design that does not incorporate required effective passive venting of I/O engine spaces. As you describe , air drawn in by the large gunwale vents would simply be pushed out into the cockpit where any heavier gas fumes could recycle down into the bilge.
Looking at an ad on Yachtworld for a 2002 285 Sundowner, I can see what appears to be 2 fairly large rectangular holes facing aft on the upper transom stbd side above where the swim platform ladder would be. Could they possibly be exhaust vents? Transom vents are often not great places for exiting vents due to the "station-wagon" effect.
When you have the blowers on , where does that exhaust? The blower vent is often shared by passive venting duct as well. But if those blowers exhaust out the forward-facing P & S gunwale vents , that would be highly improper & IMO pretty inexcusable.
Looking at an ad on Yachtworld for a 2002 285 Sundowner, I can see what appears to be 2 fairly large rectangular holes facing aft on the upper transom stbd side above where the swim platform ladder would be. Could they possibly be exhaust vents? Transom vents are often not great places for exiting vents due to the "station-wagon" effect.
When you have the blowers on , where does that exhaust? The blower vent is often shared by passive venting duct as well. But if those blowers exhaust out the forward-facing P & S gunwale vents , that would be highly improper & IMO pretty inexcusable.
The holes you are referring to are covers for the shore power switch and plug. The blower exhausts out the port gunnel intake which does face forward! Thanks for the tip about the "station wagon effect" but if I add transom vents, could they be more of a positive pressure area than the gunnel vent facing forward? It gets very warm in the compartment because when I added a recessed pole holder on the transom for a flag staff, the heat rising from it is hot. My son in-law's Sea Ray Cuddy Cabin has a transom vent that spans most of the transom so I'm not sure about the positive pressure area. Am trying to find some type of remote thermometer to determine actual temps.
Maybe just something like this inexpensive 10'corded I/O digital thermometer to compare engine space temp to ambient?
http://www.zoro.com/taylor-digital-thermometer-40-to-158-degree-f-1522/i/G1642374/?utm_source=google_shopping&utm_medium=cpc&utm_campaign=Google_Shopping_Feed&gclid=CMGfmciniMcCFYUXHwodQ_MEmQ&gclsrc="aw.ds
http://www.zoro.com/taylor-digital-thermometer-40-to-158-degree-f-1522/i/G1642374/?utm_source=google_shopping&utm_medium=cpc&utm_campaign=Google_Shopping_Feed&gclid=CMGfmciniMcCFYUXHwodQ_MEmQ&gclsrc="aw.ds
- Joined
- Sep 28, 2002
- RO Number
- 10314
- Messages
- 851
On my boat I have vents on the upper rear gunnels. They are directional stainless steel units that you can buy anywhere. The one that is connected to the blower faces aft and the one that is on the other side faces fwd and has a fresh air hose leading down into the bilge. Chapman's has a diagram of how a blower system should be sent up on an inboard gas engine and this is set up the same way