C28 Real World performance... with painted bottom

[circusmar]

We are hitting low 25's WOT and cruising @18kts (3250rmp) at ~9-9.5 gal/hr. How does that compare to the experience of others? We are an early build 2011 with a 6by2.

 

[baz]

We are hitting low 25's WOT and cruising @18kts (3250rmp) at ~9-9.5 gal/hr. How does that compare to the experience of others? We are an early build 2011 with a 6by2.

Our 2010 R-25 with the Yanmar 4BY2-150 engine drinks (numbers based on a recent cruise earlier this week)

1) 0.4 gals/hr at 4 Kts
2) 2.0 gals/hr at 8 Kts (2500 rpm)
3) 5-6 gals/hr at 14 Kts
4) 7 gals/hr at WOT (3800 rpm) 15 to 16 Kts

Our R-25's bottom is clean. Our R-25 weighs around 7,800 lbs with 180 lb Portland Pudgy dingy, full 75 gal fuel tank and full 30gal fresh water tank. When the boat was new with full fuel tank and no dingy and very little else it would go close to 19 Kts at WOT on our local Lake Washington.

 

[pleeson]

Our 2013 C28 with Volvo is topping out at 25 knots with clean gel coat and a full week long cruising load with two adults, and including rear mounted dinghy. Not bad for a 4 cyl diesel!

 

[circusmar]

Interesting, our numbers are with our boat very "light". half a tank and only minimal gear. We were expecting a bit more based on published specs. we are burning 13-14 gph at WOT.

According to the "tests" our boat should be running 29ish knots???

 

[Irish Mist]

Try different positions with the trim tabs Makes a big differance with my 29.

 

[circusmar]

Thanks Irish,

we are very comfortable with tabs and their use in varying conditions. thanks though!

we were hoping that the stepped hull might offset some of the typical bottom paint penalty. we tend to run a bit lighter than average and were a little bummed our cruising and "flanking" speeds were significantly less than "tested"/advertised. still respectable for the size/engine but not sure how much the advanced hull is really adding.