Blower Vent Hose

[Fred]

My Catalina 28 MK2 has an engine compartment blower (I presume this is standard issue) with both an inlet and exhaust hose that vents out of the stern. I need to replace the hose. The current hose looks like cheap vinyl 3" dryer vent hose. I notice that Amazon sells plastic "Black Marine Blower Hose". Is there something special about this hose rather than regular vent hose that should steer me to "marine" hose? Also --- wouldn't it be more effective (in terms of air circulation, cabin heat and odour extraction) to pull the air from the engine compartment itself (its not sealed) rather than through an intake hose. (note: I do not have AC on the boat). Thoughts?

 

[Ralph Johnstone]

Noise may be a problem under some circumstances. Read on ........................

 

[Fred]

Thanks Ralph. Interesting project write-up.

 

[Fred]

Also wondering… boats with gasoline engines I believe are required to have bilge blowers for safety purposes however I have seen several diesel powered boats that do not have them installed. What is the primary reason for the installation in the Cat 28? Is it due to the engine (e.g. cooling, odour, etc.) or is it because there is a propane system installed?

 

[jssailem]

Fred,

The existence of a bilge blower was pretty common boat building from the 70’s and became a CG requirement in the 80’s for all gasoline powered inboard boats. While not required on diesel powered boats it is a nice addition. It can help to reduce the heat in the boat due to engine usage. It will help to evacuate orders that are expected with boat usage.

Good seaman like practice is to engage the blower several minutes before starting an engine to be sure the bilges are cleared.

 

[Fred]

“Good seaman like practice is to engage the blower several minutes before starting an engine to be sure the bilges are cleared.”
That’s why I’m wondering if it’s better not to have the inlet blower hose as drawing all the air from the engine compartment/ bilge would improve evacuation of odours and gases.

 

[Ralph Johnstone]

That’s why I’m wondering if it’s better not to have the inlet blower hose as drawing all the air from the engine compartment/ bilge

To have air forced into the engine compartment is a gross error. You run the risk of forcing contaminated air into the cabin. Ensure you have an adequate free air supply INTO the engine compartment.

 

[Fred]

That’s why I’m wondering if it’s better not to have the inlet blower hose as drawing all the air from the engine compartment/ bilge

To have air forced into the engine compartment is a gross error. You run the risk of forcing contaminated air into the cabin. Ensure you have an adequate free air supply INTO the engine compartment.

I may have been unclear. I was proposing only to suck air out of the engine compartment not blow it into the compartment

 

[Ralph Johnstone]

Sorry @Fred . Lost track of whether I was coming or going in the engine compartment.

 

[Fred]

I decided to change the vent exhaust hose (hose from engine compartment to the blower). It turns out that the hose was routed straight back from the engine compartment to the inline blower which is mounted beneath the starboard quarter deck, essentially beside the fuel tank. The hose passed under a bulkhead, just aft of the removable stern berth panel. There was not enough room there so the hose was squashed and presumably the flow was restricted. I re-routed the hose underneath the fuel tank to the inline blower. The exhaust flow is significantly stronger than it was before.