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  #1   IP: 156.57.174.172
Old 01-25-2019, 06:38 AM
Joe Miller Joe Miller is offline
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Grampian 30

Hello All,

I am rebuilding the exhaust on a Grampian 30.
I intend to use the Vetus L40 water lock and matching 40mm Vetus hose.
My plan is to use black iron to create a riser at back of manifold,
up +- 8", then turn back down towards water lock using raw water mixing fitting and nipple. From here 40mm hose to H2O lock and then to stern.
I plan to put a rise in the hose before the exit point in the stern as it is quite low.
I appreciate any input regarding design.

Thanks,

Joe
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Old 01-25-2019, 10:10 AM
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ndutton ndutton is offline
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If you put the high point in the exhaust hose as soon after the waterlift as possible you will minimize the backwash into the waterlift when turning the engine off.

I'd be interested in learning what features of the Vetus LP40 factored into your decision to use it.
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Old 01-25-2019, 05:54 PM
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The water injection point should be at least 4 inches lower than the high point of the hot loop. More is better. This minimizes moisture migration back to the manifold, which would encourage sticking valves
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Old 01-29-2019, 06:06 AM
Joe Miller Joe Miller is offline
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exhaust

Hello Neil, the Vetus was chosen mostly on cost, although quite a few are in use and seem to work well.
Ed, I should be able to get the separation you mention, I will check next time I am on the boat. I may have to create a small heat shield on the underside of the bridge deck to get a little more height.

Thanks for the input.

Joe
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Old 01-29-2019, 07:42 AM
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Take a look. The red design sends a lot more water back towards the water lift than the green design.
Take care with the Vetus, I have one too and it works great as long as it gets cooling water. It will melt quickly if run dry I have a fiberglass Centek (sp?) version in my shed I might install one of these days.
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Old 01-29-2019, 08:52 AM
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The Catalina 30 (over 7000 boats built) exhaust system is close to being a compromise of the drawing with the high point about mid way between Joe's red and green lines. During my recent exhaust work I noticed there is barely a splash of residual water in the waterlift after a normal shut down (a good thing) BUT it also has a check valve before the high point. In later model years Catalina did away with the check valve in favor of a high volume waterlift of their own in-house manufacture. Unfortunately their big waterlift has known weaknesses of side panel flex and base seam failure. They were better off with the check valve and smaller outside-sourced waterlift.

Joe's caution about the Vetus's intolerance of abnormally high operating temperature is noted. To that end, please consider at least the basic MMI alarm system (oil pressure and temperature with a buzzer alert) with the raw water flow sensor added. A loss of raw water flow is swift death to a Vetus so the more carefully you monitor it, the better.
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Old 01-30-2019, 07:16 AM
Joe Miller Joe Miller is offline
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My exhaust should look some what like the green line in Joe' diagram with following difference.

I will come off the back of the manifold, then 90* up, over the top, water injection after the upper turn and then down to Vetus lift about 12"away, then towards the stern with another upward loop in the hose only, and then discharge out the stern. The discharge is close to the waterline so the second rise is to stop flooding from following seas.
Will the two loops create too much back pressure in the exhaust and is the second even needed? I would like a Cetek but the cost is just way to high here in Canada

Thanks again,

Joe
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