Cruisers Forum
 


Reply
 
Thread Tools Search this Thread Rate Thread Display Modes
Old 24-11-2021, 11:58   #16
Registered User
 
rgleason's Avatar

Join Date: Mar 2012
Location: Boston, MA
Boat: 1981 Bristol 32 Sloop
Posts: 15,512
Re: Yanmar Exhaust - Bristol 32

@Cheechako,
12"-16" dia loop is something I'll keep in mind but would not want to crimp it. Thanks. It's a pretty small lazerette because the tail is small, also I might need some extra hose, so adding the U might work out better... we will see.

I think I'll take progress photos and upload here as I get into it.

@compass
Your ss welding looks quite good. Unfortunately I don't have a reliable SS welder here who does not cost beaucoup bucks. I am interested in the raw water connection. Is that just a straight hose connection about 3" down from the elbow?
Also is this type of T connection frequently used and reliable insofar as not getting raw water up into the manifold?
rgleason is offline   Reply With Quote
Old 24-11-2021, 12:46   #17
Registered User
 
Cheechako's Avatar

Join Date: Aug 2006
Location: Skagit City, WA
Posts: 24,218
Re: Yanmar Exhaust - Bristol 32

Quote:
Originally Posted by rgleason View Post
@Cheechako,
12"-16" dia loop is something I'll keep in mind but would not want to crimp it. Thanks. It's a pretty small lazerette because the tail is small, also I might need some extra hose, so adding the U might work out better... we will see.

I think I'll take progress photos and upload here as I get into it.

@compass
Your ss welding looks quite good. Unfortunately I don't have a reliable SS welder here who does not cost beaucoup bucks. I am interested in the raw water connection. Is that just a straight hose connection about 3" down from the elbow?
Also is this type of T connection frequently used and reliable insofar as not getting raw water up into the manifold?
In my opinion it's always better to not piece things together. Shields exhaust hose:
Attached Thumbnails
Click image for larger version

Name:	ShieldsBend.jpg
Views:	10
Size:	356.0 KB
ID:	248808  
__________________
"I spent most of my money on Booze, Broads and Boats. The rest I wasted" - Elmore Leonard











Cheechako is offline   Reply With Quote
Old 24-11-2021, 12:55   #18
Registered User
 
rgleason's Avatar

Join Date: Mar 2012
Location: Boston, MA
Boat: 1981 Bristol 32 Sloop
Posts: 15,512
Re: Yanmar Exhaust - Bristol 32

I see your point, also less back pressure. If I can fit it, I will do it that way, and the top of the hose loop will be right against the underside of the deck. I expect there may be a 60 degree to horizontal drop of the pipe, down to the outlet.


One question that occurs to me is if the previous hose was 1.5" and this one is 2" as required by Yanmar, then shouldn't I replace the outlet fitting to be 2" so that there is no increase in back pressure?
rgleason is offline   Reply With Quote
Old 24-11-2021, 18:52   #19
Marine Service Provider

Join Date: Sep 2014
Location: Auckland, NZ
Boat: Compass 790 , 7.9 metres or 26 ft
Posts: 2,631
Re: Yanmar Exhaust - Bristol 32

@compass
Your ss welding looks quite good. Unfortunately I don't have a reliable SS welder here who does not cost beaucoup bucks. I am interested in the raw water connection. Is that just a straight hose connection about 3" down from the elbow?
Also is this type of T connection frequently used and reliable insofar as not getting raw water up into the manifold?[/QUOTE]

Actually that was pretty ugly stick welding, if i'd had a pulse TIG or a mig it would be prettier but its effective.
Yes thats a straight hose connection. I angled it downwards so water cant go up. It has proved to be problem free for a few years now. Yes I've seen more like that.
Its much better than yanmars design that relies on the integrity of the inner wall to stop raw water getting into the manifold. See attached pic
Mind you I dont know if your 3ym30 has the same type of elbow.
Sorry couldnt attach image but if you go to page 3 on this thread you will see a cutaway of mixing elbow, https://www.cruisersforum.com/forums...-103029-3.html
I would put an outlet fitting to match hose size but i'm not expert enough to say wether it is essential.
Compass790 is offline   Reply With Quote
Old 24-11-2021, 19:20   #20
Registered User
 
rgleason's Avatar

Join Date: Mar 2012
Location: Boston, MA
Boat: 1981 Bristol 32 Sloop
Posts: 15,512
Re: Yanmar Exhaust - Bristol 32

Compass Very interesting.... the standard elbow gets clogged up and raw water could break through the barrier in time.....

I think this is the cutaway shot you were referring too in Post #31
https://www.cruisersforum.com/forums...ml#post1226763

How he put it back together temporarily
https://www.cruisersforum.com/forums...ml#post1226340 #26

This UK fellow makes them for Yanmar
https://www.exhaustelbow.com/
Shows various raw water introduction ports.

It will be a good idea to insulate the upper part of the riser, particularly before the raw water is introduced.

Replacement every 5 years? I've gone 8 years, 750 hrs....??
https://www.cruisersforum.com/forums...ml#post1225697
rgleason is offline   Reply With Quote
Old 24-11-2021, 19:41   #21
Registered User
 
rgleason's Avatar

Join Date: Mar 2012
Location: Boston, MA
Boat: 1981 Bristol 32 Sloop
Posts: 15,512
Re: Yanmar Exhaust - Bristol 32

Here is an alternative perspective
https://www.cruisersforum.com/forums...ml#post1767028
rgleason is offline   Reply With Quote
Old 24-11-2021, 23:17   #22
Marine Service Provider

Join Date: Sep 2014
Location: Auckland, NZ
Boat: Compass 790 , 7.9 metres or 26 ft
Posts: 2,631
Re: Yanmar Exhaust - Bristol 32

Quote:
Originally Posted by rgleason View Post
Compass Very interesting.... the standard elbow gets clogged up and raw water could break through the barrier in time.....

Believe me it does corrode thru the barrier, I've seen a few die that way

I think this is the cutaway shot you were referring too in Post #31
https://www.cruisersforum.com/forums...ml#post1226763

Yes thats right


How he put it back together temporarily
https://www.cruisersforum.com/forums...ml#post1226340 #26

Good on him.

This UK fellow makes them for Yanmar
https://www.exhaustelbow.com/
Shows various raw water introduction ports.

Yes I dont think tube that exhaustelbow.com uses is as good as sched 10 pipe as its much thinner, more prone to cracks, less life & has to be welded with TIG
I would buy the HDI marine investment cast 316 if you cant get one made cheap as its a lot thicker but I think its a direct copy of Yammers elbow so it has the same potential for raw water to get in the head.
It should be possible to make one out of threaded fittings too.


It will be a good idea to insulate the upper part of the riser, particularly before the raw water is introduced.

Yes i did that with ceramic wrap but didnt mention it

Replacement every 5 years? I've gone 8 years, 750 hrs....??
https://www.cruisersforum.com/forums...ml#post1225697
Yes they last longer than maintenance sched but my last ss exhaust did 15+ years but sold boat so not sure after that.
Again I say if you leave yanmar elbows on till they fail you are likely to get raw water in the head whereas it cant happen with the type I used.
Dont know how long Yanmar elbows last in practice.
Yanmars elbows are 2x the USA price here.
Compass790 is offline   Reply With Quote
Old Today, 16:46   #23
Marine Service Provider

Join Date: Sep 2014
Location: Auckland, NZ
Boat: Compass 790 , 7.9 metres or 26 ft
Posts: 2,631
Re: Yanmar Exhaust - Bristol 32

Forgot to add a better design than mine I will attach a very rough pic of.
It has the advantage of distributing the raw water all around the pipe for better cooling..
Also it makes sure no raw water can splash up.
I didnt bother with the added complexity as we only have an 8hp diesel & dont have a high heat load so I guessed it would be ok. Would have gone down the pictured path on a motor maybe your size as maybe you might scorch the exhaust hose with no inner pipe but again its just a guess.
Attached Thumbnails
Click image for larger version

Name:	20211129_121507.jpg
Views:	4
Size:	271.7 KB
ID:	249013  
Compass790 is offline   Reply With Quote
Reply

Tags
exhaust, yanmar

Thread Tools Search this Thread
Search this Thread:

Advanced Search
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
Motoring across the Bristol Channel - Swansea to Bristol schtompenbroner Europe & Mediterranean 1 22-05-2019 11:20
Rudder needed for Bristol 29/Bristol 30 Sun and Moon Construction, Maintenance & Refit 15 31-01-2014 09:57
For Sale: Bristol Yachts Bristol 32 Arclight Classifieds Archive 0 04-04-2010 07:41

Advertise Here


All times are GMT -7. The time now is 23:30.


Google+
Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2021, vBulletin Solutions, Inc.
Social Knowledge Networks
Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2021, vBulletin Solutions, Inc.

ShowCase vBulletin Plugins by Drive Thru Online, Inc.