69 45C with 8-71N speed

[madhatter1]

Anyone have speed and fuel numbers for this config? If we move forward and rebuild the engines to stock specs what would hull speed/NMPG, cruise speed/NMPG, and top end/RPM be? If project is done the props and bottom will be new and years of accumulated junk will be gone. Thanks in advance.

 

[jim rosenthal]

Top speed would be, I think, about 15-18 knots. I don't think it would go any faster than that, even on a diet, with a clean bottom and fresh engines.

 

[hyperfishing]

How many hours on the 8-71N before rebuild?

 

[saltshaker]

16.5-17kt cruise at 2100rpm and 28gph
19.5-20kt WOT 2300rpm and 40gph
That's how my 46C ran with the 8V71N's. The 45C is typically a hair faster but not much.

 

[dsharp]

With 2:1 gears and no tower it should run 15-18. I ran one with 1.5 to 1 gears with a tower and I don't think it made 13 kts. That's a heavy boat but if you keep the weight off they run alright with naturals. It depends if your comfortable running it 2100 rpm vs 1800 rpms. I like them better at 1800.

 

[saltshaker]

With 2:1 gears and no tower it should run 15-18. I ran one with 1.5 to 1 gears with a tower and I don't think it made 13 kts. That's a heavy boat but if you keep the weight off they run alright with naturals. It depends if your comfortable running it 2100 rpm vs 1800 rpms. I like them better at 1800.

1800rpm is lugging it for the naturals and particularly for that boat. Those engines will run forever at 2100rpm. Even at WOT, they're making less HP than an 8V71TI at cruise. In heavy seas I would run mine WOT for extended periods. Only way to keep her on top of the water and properly cut through seas. I would never do that with the 6V92TA's I re-powered her with. Those engines would push her along nicely at cruise so no need to push them that hard.

 

[madhatter1]

Jack, What was RPM/GPH at hull speed. I figure the 45 would be 8.5kts. Thanks, Mike.

 

[rsmith]

16.5-17kt cruise at 2100rpm and 28gph
19.5-20kt WOT 2300rpm and 40gph
That's how my 46C ran with the 8V71N's. The 45C is typically a hair faster but not much.

You had N's in your 46?????
TI's were standard equiptment in late 73 45's 74 45's and 74 46's from what I remember. I've run offshore canyon charter trips on each of these boats back in the day when they where "new" the 45 with n's was 15kts @2100 the 46 would run 19.5 @2100 and the 45 with TI's would run a little bit faster than the 46 cause it was 1900lbs lighter. None of these were tower boats or "bloated " liveaboards. Dont remember actual fuel burns but totals for a day trip leaving the sea bouy at Cape May 4:30 am, lines in the water at 8:30 troll till 3pm and back at the dock at 7pm would pretty much concistantly run 325 gal for the 45 with N's 365gal for the 45 &46 with TI's and 485 for my old 50 with the 12v's.

 

[saltshaker]

You had N's in your 46?????
TI's were standard equiptment in late 73 45's 74 45's and 74 46's from what I remember. I've run offshore canyon charter trips on each of these boats back in the day when they where "new" the 45 with n's was 15kts @2100 the 46 would run 19.5 @2100 and the 45 with TI's would run a little bit faster than the 46 cause it was 1900lbs lighter. None of these were tower boats or "bloated " liveaboards. Dont remember actual fuel burns but totals for a day trip leaving the sea bouy at Cape May 4:30 am, lines in the water at 8:30 troll till 3pm and back at the dock at 7pm would pretty much concistantly run 325 gal for the 45 with N's 365gal for the 45 &46 with TI's and 485 for my old 50 with the 12v's.

Mine was one of only 3 or 4 that were ordered with 8V71N's. I've heard there were a couple with Cummins VT903's but I've never seen one. My 46 was definitely underpowered with the naturals. She would have a hard time staying on plane in a head sea unless you ran her on the pins. That's the reason why I put the 550HP 6V92's in her.

 

[captddis]

I was told that some of the early 53C's had 8v71n in them.

 

[saltshaker]

I was told that some of the early 53C's had 8v71n in them.

They must have ran like trawlers.

 

[rsmith]

They must have ran like trawlers.

The famous Dutchess of Walkers Cay had 8'ns. Billy Black bought her in Trinidad in 1976 and fished almost everyday for 30 years putting 40,000 hours on the engines. 11kts was about as good as it got.

 

[GOLE IV]

Before repower my 1973 45c series I made 17 knt by gps right after doing the bottom @wot. (8v71n)
Previous owner claim 18 knt measure the old way?

Fuel consumption close to previous post, but don't remember

With the yanmars, now 27 knt @ wot

 

[dfirst hatt]

I have 1970 45c series 1 w/8v71n's.Clean bottom fresh water loaded or not makes 19- 21 knots at 2050 governed,rpm's fuel guess 35-40hr. approx 3000 hrs on mtrs. will plane at 1300, 13-15 knots great runners even better sound.Good luck Dave

 

[Boatsb]

I have 1970 45c series 1 w/8v71n's.Clean bottom fresh water loaded or not makes 19- 21 knots at 2050 governed,rpm's fuel guess 35-40hr. approx 3000 hrs on mtrs. will plane at 1300, 13-15 knots great runners even better sound.Good luck Dave

That seems loss for wot. I thought the engines should then 2300 or more.

My 8v53n then 2650 or so at wot. 2700 with everything clean and pristine.

 

[Scope]

With a few modifications to running gear,18knts cruise add 660hp cats 26 cruise 28gal. per hour and 33 on the pins thats with 1.75 to 1 gear and 28x34 props.

 

[Vincentc]

With a few modifications to running gear,18knts cruise add 660hp cats 26 cruise 28gal. per hour and 33 on the pins thats with 1.75 to 1 gear and 28x34 props.

Is that 28 gph at 26 it's both engines?

 

[Scope]

28gph @ 26 knots Total fuel burn.

 

[Vincentc]

Impressive.

 

[Boatsb]

Is that 28 gph at 26 it's both engines?

That sounds too good to be true for a series 1 45 c. A neighbor had one with the big cats and burned mid 30's at a 25 k cruise.