dinghy problem with weaver davits on a 27

[mac07733]

I have a 27 that I have added Weaver Davits. I have just under 250 hours on the engine. It seems that, because of our schedule (or maybe my personality) that we are spending most of the time cruising at 15 mph. The boat has performed superbly however my dinghy on the davits is heavily discolored (bottom tube port side - from the exhaust ) and most recently, the tube is being melted (no blow out yet!). I am thinking of putting some sort of sleeve on it when I am running. Has anyone else had a similar issue? Any suggestions? The dinghy is a 7 1/2 ft with a hard bottom. It fits well on the back of the boat.

 

[Levitation]

What? Melting the Hypalon while it is up on the swim step? Is your water muffler working? (better inspect your exhaust hose at the water injector) There is something major wrong here... Pictures please...

 

[Dale777]

I have a 27 that I have added Weaver Davits. I have just under 250 hours on the engine. It seems that, because of our schedule (or maybe my personality) that we are spending most of the time cruising at 15 mph. The boat has performed superbly however my dinghy on the davits is heavily discolored (bottom tube port side - from the exhaust ) and most recently, the tube is being melted (no blow out yet!). I am thinking of putting some sort of sleeve on it when I am running. Has anyone else had a similar issue? Any suggestions? The dinghy is a 7 1/2 ft with a hard bottom. It fits well on the back of the boat.

I also have an R27 with an 8-1/2 foot hypalon rigid bottom dinghy mounted on the swim platform with Weaver Davits. However, I've just now got the dinghy and davits in place and working, but with no time spent running with this arrangement. Therefore, I'm curious to know if I might begin to experience the same problem mentioned by mac07733 with exhaust discoloring or melting the dinghy tube.

Any update on this issue?

 

[sportner]

We have 330 hours on our boat and use weaver davits also. We have exhaust stains that we clean occasionally but have not had any melting. We run at 6-7 knots 75% of the time. I think the stains are probably normal but melting seems unusual.

 

[ozoner]

+1 What Leviation said.

If the exhaust is hot enough to be melting the dinghy tube after exiting under the swim step and mixing with the air, then it is certainly hot enough to be charring the rubber exhaust hose also. You definitely want to check that you have enough water flowing into your exhaust manifold; replace your exhaust hose if you find a problem. The excess heat caused by reduced water flow chars the inside and makes the hose very brittle.

 

[trailertrawlerkismet]

A damaged impeller could create exhaust that is hotter then normal therefore this should also be checked. Please let us all know what the outcome and or remedy is.

Jim

 

[wefings]

If there were an engine running problem [over heating] it would likely show up on the display .
Might want to add some fuel treatment [injector cleaner] to see if it cleans things up .
Marc

 

[rwetjen]

After burning thru the exhaust hoses on a Tollycraft years ago, I'd never run a water cooled exhaust without a temperature alarm. The hoses burned thru before engine temp began to rise. If any part of the exhaust hose feels warm running at speed, there's a problem. On my '07 R-21 (750 hours) I've added a Borel exhaust hose temp alarm (http://www.borelmfg.com/). Also replaced the stock cast iron riser with a custom inconel unit and the rubber hose (riser to muffler) with blue silicone high temp hose. Overkill? Maybe, but the morning that I forgot to open the engine seacock it saved me a big repair bill. The temp alarm went off right after I throttled up coming out of the marina. Even the impeller survived that dumb move. Exhaust temp problems can happen suddenly or build up slowly over time. The latter usually due to rust build up in the water injection ports of a cast iron riser.

 

[Andrew Custis]

The exhaust water should be nowhere close to melting temperatures. We install quite a few inflatables on the tugs as they leave the factory and I have seen the staining from the exhaust but never anything melted. If I remember right on some of my testing, I shot exhaust water temps at somewhere close to 120 degrees. I agree with Jim's idea of checking the impeller first. Marc is also correct on watching your instruments to see what kind of temperatures that Yanmar is running at. 200 degrees is pretty normal depending on water temp.

 

[mac07733]

After working to clean the discolored stain with rough bumps (which I mistook for melting), I have discovered it is all removable. Thank you everyone for your comments. Happy New Year