Cruisers Forum
 


Join CruisersForum Today

Reply
 
Thread Tools Rate Thread Display Modes
Old 18-07-2015, 05:08   #1
Registered User
 
sanibel sailor's Avatar

Join Date: Feb 2013
Location: Sanibel FL
Boat: 1979 Bristol 35.5 CB
Posts: 978
Deck hole size for dorade box

My current Dorate boxes are shot. They have 3 inch Cowls. I'm building new ones fitted with 4 inch cowls.I am planning on enlarging the hole in the deck as well. I'm going to use PVC pipe for this with a threaded fitting on the inside. This will allow me to shut it off with a plug if needed. I'm considering whether to use 4 inch or 6 inch pipe. Four-inch matches the vent. Six inch has less restriction and might let in in more air and has a higher lip, perhaps preventing water intrusion better.The 6 inch just looks awful big however. Any thoughts on an oversize deck pipe?
Attached Thumbnails
Click image for larger version

Name:	image.jpg
Views:	106
Size:	403.3 KB
ID:	105553  
__________________

__________________
John Churchill Sanibel FL
NURDLE, 1979 Bristol 35.5 CB
sanibel sailor is offline   Reply With Quote
Old 18-07-2015, 07:19   #2
Registered User
 
Sailormantx's Avatar

Join Date: Sep 2012
Location: Newfoundland
Boat: 42' Colvin Gazelle
Posts: 253
Images: 2
Re: Deck hole size for dorade box

The size of the cowl determines amount of airflow. I have installed the same on my boat and it works well. I have 5" cowls and 4" pipe fittings as I could not find any in 5" and thought that 6" was too big. The part projecting above deck is also a good place to hose clamp some bronze screen to keep bugs out.
__________________

__________________
Sailormantx is offline   Reply With Quote
Old 18-07-2015, 07:52   #3
Registered User

Join Date: Nov 2013
Location: Detroit
Boat: Tahitiana 32
Posts: 44
Re: Deck hole size for dorade box

Use the 4". If you want greater airflow, install a solar powered ventilator cap.

Marinco, 4" Day / Night Plus Vent Solar Light w/ Stainless Steel Cover, N20704S
__________________
georgelieber is offline   Reply With Quote
Old 18-07-2015, 15:38   #4
Moderator
 
JPA Cate's Avatar

Join Date: Nov 2011
Location: aboard, cruising in Australia
Boat: Sayer 46' Solent rig sloop
Posts: 10,710
Re: Deck hole size for dorade box

Hi, John,

The 4" will do noticeably better than the old 3". The cowl size (as mentioned above) is the limiting factor.

For underway in hot, steamy places, I'm a greaty fan of fans, strategically placed, for making life below decks better.

Also, for at anchor where it rains a lot, we made a hatch dodger that works on the dorade principle, and can leave the hatch open up to about 25 knots, after that, the wind blows the bouncing rain drops in, below that, it allows a lot of air in.

Ann
__________________
Ann, with Jim, aboard US s/v Insatiable II, in Oz, very long term cruisers
JPA Cate is online now   Reply With Quote
Old 19-07-2015, 11:26   #5
Registered User
 
Cadence's Avatar

Join Date: Dec 2008
Location: SC
Boat: None,build the one shown of glass, had many from 6' to 48'.
Posts: 6,063
Re: Deck hole size for dorade box

Sailormantx had a great suggestion with the screen If you have the room go with screen and a six inch since the screen will inhibit air flow.
__________________
Cadence is online now   Reply With Quote
Old 20-07-2015, 08:00   #6
Registered User

Join Date: May 2008
Posts: 33
Re: Deck hole size for dorade box

[QUOTE=Ann T. Cate;1871866]Hi, John,

"The 4" will do noticeably better than the old 3". The cowl size (as mentioned above) is the limiting factor."

Roger that, the difference between the 3" and 4" diameter pipes results in nearly twice the area (12.6 vs. 7.1 square inches) and thus nearly doubles the potential airflow.

Sojurnr
__________________
Sojurnr is offline   Reply With Quote
Old 20-07-2015, 08:33   #7
Registered User
 
sanibel sailor's Avatar

Join Date: Feb 2013
Location: Sanibel FL
Boat: 1979 Bristol 35.5 CB
Posts: 978
Re: Deck hole size for dorade box

And I just pulled the trim ring and looked at the old deck fitting which measures about 2 1/2" ID. Four inch will be almost 3 times the area.

The limiting factor will be the size of the cowl, but restrictions are cumulative. Six is still an awfully big hole in the deck. I will go with 4" and can always make it bigger if needed. Bronze screen hose clamped to top is a great idea. I had been playing with ideas to make the screen pretty from the inside. Outside seems best.
__________________

__________________
John Churchill Sanibel FL
NURDLE, 1979 Bristol 35.5 CB
sanibel sailor is offline   Reply With Quote
Reply

Tags
deck, size

Thread Tools
Display Modes Rate This Thread
Rate This Thread:

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
Filling a six inch deck hole to 3 inches antongm Construction, Maintenance & Refit 5 07-08-2013 21:39
Installing a dorade box details - questions Abrain Construction, Maintenance & Refit 3 22-06-2013 21:11
Hole size between freezer and refrigerator? andreas.mehlin Construction, Maintenance & Refit 6 23-10-2012 15:40
Cutting a hole in my deck hatch Waterborn Monohull Sailboats 15 26-04-2009 21:11
transducer hole size csamsail Marine Electronics 4 05-01-2009 19:24



Copyright 2002- Social Knowledge, LLC All Rights Reserved.

All times are GMT -7. The time now is 16:25.


Google+
Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2017, vBulletin Solutions, Inc.
Social Knowledge Networks
Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2017, vBulletin Solutions, Inc.

ShowCase vBulletin Plugins by Drive Thru Online, Inc.