Exhaust System Diagram (New System)

[SkiprJohn]

I invite comments concerning my new design. Still a question about a valve for breaking waves over the port side but I think this should prevent water intrusion without a valve.
Thanks.

[NCboatrx]

Hello John,
This looks like a good and safe system. If you want, you could fit an exhaust thru-hull with a flap and turn it through 90 degrees to get the hinge at the forward side of the circle. This way, it should be closed when you are sailing.
Good luck, Stanley

[chala]

SkiprJohn

why the SS tube? a suitable rubber hose will be better at absorbing vibration and movement between the motor and the water lifter and does not rust.

[Stevens 47]

SkiperJohn, I thought the max height from the bottom of the waterlift to the goose neck was 42". There is a diagram on page 379 of Nigel Calders book Boatowners and Mechanical Manual. Looks like you are using Vetus parts I had a look in their catalog looks like they are showing a max of 5' so a discrepancy occurs.

[cal40john]

Practical Sailor says a max rise of 33" to prevent excessive backpressure.

Pick your favorite authority, but you're above the max on the most liberal in a situation where less back pressure is better short of not having the loop high enough.

This article, as well as Calder's book also shows how to mount the muffler higher.

http://www.practical-sailor.com/mari...iftmuffler.pdf

John

[Stillraining]

Originally Posted by chala

SkiprJohn

why the SS tube? a suitable rubber hose will be better at absorbing vibration and movement between the motor and the water lifter and does not rust.

Agreed...your asking for trouble here IMHO

[SkiprJohn]

Thanks to all who responded for the the comments.

I checked the Vetus recommended height from base of waterlift to top of gooseneck and they say it should be no more than 150 cm (59"?) which I translated incorrectly. I'll definitely lower the gooseneck. That makes the angle to the outlet a bit less but still doable.

I will try to find rubber exhaust hose that is flexible enough to make the bends I need. Stainless tubing can be bent to the proper angles. Anyone have a brand or fitting recommendation for the exhaust hose? I have to order everything via catalog.

Thanks CalJohn, I did consult that article before taking the Vetus recommendation as authority. 59" inches is probably a bit too high and 33" might be a bit too low and I'll try to find a happy medium.

[GordMay]

If you find that you must use pipe to effect the necessary bends, add a flexible hose nipple at each end (muffler & hull), for vibration isolation.

Trident ➥ Trident Marine: Wet Exhaust Hose
Gates ➥ Gates Industrial Marine Transfer Wet Exhaust Hose

[sailvayu]

I have to agree with the others and lose the SS tube from the engine to the lift. if you can draw an imaginary heeled water line at what you think would be your max heel. Say decks awash half way. If you place the top of the LT a inch or so above that what would that give you as a hight above the waterlock? If it is with in limits that is where I would put it. If not might need to make so other changes. I have always used 48" as a rule of thumb and have not had problems with that.

Wayne Cannig AMS\projectboatzen.com

[SkiprJohn]

Thanks to all for the replies. All great ideas and comments. I will do as you suggest. I talked with a power boat builder here in town and he says that vernatube is a pretty good product for exhaust systems using hose on both ends for flex.
regards,

[Stevens 47]

If you want a hard section you can use fiberglass tubing. Cut it to the angles that you want glue it with hot glue gun then wrap the bend with cloth and epoxy. That should cost you less than a SS section. I am fabing a complex section into my exhaust system using this method. I agree with Gords suggestion of using flexible hose to join hard sections. Connectors

[SkiprJohn]

For Stevens 47,
I've been looking for fiberglass tubing and have not found a source yet. What you suggested is exactly what my power boat guy suggested. Could you give me a clue as to which catalog company has tubing available?
Tomorrow I'm calling Fisheries up in Seattle to see if they can send some.
Thanks

[cal40john]

Fire resistant fiberglass tubes and fittings by the same company that makes Centek mufflers.

Centek Industries - Products

Search of Centek at Fisheries. They seem to carry most of the Centek line.

Fisheries Supply Search: centek

John

[SkiprJohn]

Thanks John. I'll be calling around tomorrow. I'd certainly like to find a source that will sell me less than 10ft and use USPS to mail it to me. Even though there is water all around me there aren't any marinas or significant marine stores within 100 miles. I need 2" and most catalogs don't show it.
regards,

[Stevens 47]

I buy it through San Diego Marine Exchange. San Diego Marine Exchange: marine products, marine equipment, marine they will cut it to the length you require.