Posted: April 09 2010 at 16:53 | IP Logged

I have a pair of detroit 671Ns in my 40' viking convertable. i'm not a speeder,but trolling around, cruising the bay, I burn 5 gal. per hr. including the 8KW westerbeke gen set. This is a five year average. Port engine is original with 3600 hrs. the starboard with about 500 hrs.

No way you can do that with gas engines!

Posted: April 13 2010 at 18:57 | IP Logged

Amen on the 671's.  I have a viking 43 double cabin MY with 671-N's and cruising at 12 MPH (hull speed) I burn 6 gals/hr. and at 20 MPH I burn 20 gal/hr.  That's not really bad for a boat that cranks in at 19 tons. 

Love the boat.

Bob

Posted: April 26 2010 at 08:48 | IP Logged

I would love to hear an answer to this question.  Also, has anyone tried to put sound barrier material around the exhaust tube raceway (backside of mufflers) or have they installed any sound barrier material in salon flooring/hatches??

Thanks

Bob

Posted: April 26 2010 at 09:26 | IP Logged

I tried several ways, styrofoam sheeting, expandable foam, foil backed, etc. it helped very little. Seems all the clatter from the injectors etc just resonates thru it all. plus the fact they vent below the deck makes it even harder to tone them down.

I still say the longevity, economy, cost to rebuild or replace make it all worth while!

Posted: April 26 2010 at 10:11 | IP Logged

I would guess that 95% of the noise is coming out of the exhaust.  Other boaters know I've started up my 671's from 3 docks away.  There is engine room noise but not that bad.  Exhaust tube raceway doesn't seem that bad either.  I think the secret is finding a muffler that will quite 2-stroke engines without adding to the back pressure.

Marv

Posted: April 26 2010 at 12:02 | IP Logged

Thanks guys for the response.  I also love my 1980 43 aft cabin with hardtop on aft deck and agree that you can't have a conversation on the aft deck when motors are running.  As far as a different muffler, based on where they are and how much space is considered extra in that area, I'm not sure how many configurations would be available to support a different style muffler.

I guess with everything so right with these motors a little noise is worth putting up with.

Posted: April 28 2010 at 07:57 | IP Logged

Picture of CherBo (1980 43 Viking DCMY) coming home from Saint Michaels on the Cheasapeake last summer.

 Can't wait to get her out this year.

Bob

Posted: April 29 2010 at 07:57 | IP Logged

Lou, open an account in Photobucket (it's free), upload some of your pictures and choose one to bring to website.  Under the [share the image] you have 4 options, choose the IMG Code, copy and past in boat us (when you paste you will see only the code but when you [Preview Post] you will see the picture. 

So, let me see what you got.

Posted: April 29 2010 at 14:33 | IP Logged

THANKS FOR THE INFO. I'M GONNA GIVE IT A TRY AS SOON AS I GET SOME FREE TIME.

I GOT AN AWSOME PICTURE TAKEN FROM A HELICOPTER. HOPE IT COMES OUT OK. LOU