Need replacment for blower grille covers

Summerrental

On my 2005 Rinker 270, I have 4 plastic blower exhaust grilles in the rear of the boat. 2 on port side and 2 on starboard side. They are secured using screws from the topside.  Over the years the sun has caused them to get brittle and they are breaking. Would love to find exact replacments.  Even better, I would love to find exact replacments in stainless / chrome so I don't need to do this again.  Thanks for any help!!

Handymans342

Here is what I used. Just google 4 inch vent covers. I also added screening on the inside to keep out the wasps

Summerrental

Look like I found them on Amazon or ebay for about 11 each. Not bad.  How are they secured? 

Handymans342

I used 4200

Cableguy Greg

http://www.replacementboatparts.com/VentGrills.aspx

NRath

I can't say that I exactly understand how it goes together, but it looks pretty good.  It takes a contortionist to get the hose slid on and a zip-tie around the factory set up.  I assume it'll work and can figure it out when it's in hand to look at.  I will be going for these (I need 3").
http://www.replacementboatparts.com/ventgrill3ssdomed.aspx

My only other question on it is that 2 of the vents were as you pictured summerrental, the other 2 were completely open.  And, not just the center broken out of them.  One of these 2 is the one with the blower.

Ok, one more.  Newbie question... Should I keep the fan on when running also, or just for 4 mins prior to start up?  I don't see that there is any forced induction of air from a vent while moving.

MarkB

Keep the blower running. The blower will create a negative pressure in the engine compartment and at least keep fumes from entering in the cockpit. It also will help the engine compartment run a bit cooler.

Dream_Inn

Some blowers are not made for continuous operation.  I run mine before I start and while at idle.  I also run them while using the generator (I know some that only run it initially for the generator as well).