Grubby bum

[Robin]

Our newto us Birchwood TS 37 with twin Yanmar 6PLA 260hp donks doesn't smoke on startup or visibly underway but on our delivery trip from Dartmouth to Lymington we seem to have collected a grey transom and grey bottom to the RIB in davits on the stern. The exhaust are strange with the outlets in hull mouldings at water level on the side of the stern. At speed the wake blows around the back end and presumably carries sooty water droplets with it. Is this normal, should I be concerned, is there anything I can do to reduce it other than go slower?

 

[fred247]

Our newto us Birchwood TS 37 with twin Yanmar 6PLA 260hp donks doesn't smoke on startup or visibly underway but on our delivery trip from Dartmouth to Lymington we seem to have collected a grey transom and grey bottom to the RIB in davits on the stern. The exhaust are strange with the outlets in hull mouldings at water level on the side of the stern. At speed the wake blows around the back end and presumably carries sooty water droplets with it. Is this normal, should I be concerned, is there anything I can do to reduce it other than go slower?

Pretty normal, ours always did the same when on the plane, just get used to cleaning it, for whats its worth our phantom does just the same.

 

[Robin]

Pretty normal, ours always did the same when on the plane, just get used to cleaning it, for whats its worth our phantom does just the same.

Thanks, looks like telescopic mop is on the shopping list then.

 

[rafiki_]

Yep, we get this on our Azi when the sterngear is fouled, and the engines are working harder.

 

[Robin]

Yep, we get this on our Azi when the sterngear is fouled, and the engines are working harder.

This was just a week after survey and lift /pressure wash so should have been clean enough, bottom is coppercoat too. Perhaps we are a little overpropped although it pulls max revs in gear. Most likely we need to be less lead footed. We were experimenting a little and found getting her well up planing then backing off enough to just keep there gave us 15.4kts effortlessly which is fine and what the previous owner cruised at in exchange for 35l/h /engine, pretty much what we saw ourselves on the flowscans

 

[David435]

We had this on our Princess 435 but found using Soltron as a fuel additive reduced the carbon deposits on the stern. We still have to clean on a regular basis but not quite so hard.

 

[Robin]

we had a similar grey film effect on our sailboat with a 44hp yanmar if we had a tailwind so it seems to be an airflow induced effect and perhaps influenced by the stern configuration and RIB hanging in davits. Possibly we could have had more bow down trim applied but thought we had that about right. We are now live aboards so plenty of gear adding to our weight too

So accepting the inevitable what is best to clean it off with, minimum effort is good?.

PS I used Soltron for years and like it, this time the previous owner used fuel set or similar and we just used that on fill up as some was left on board.

 

[5teve]

Exhaust sound similar to ours. After a single run of about 2 hours is got a defined shadow on it (locally built boat) having looked at it running on the plane, the exhausts get fully covered by the wake but also spray the wake and soot up the side. I'm wondering about experimenting with a spray rail tacked on to see if I can divert the water away from up the side...


Steve