Diesel Engines

[NeilB]

1 hour ago, Vaughan said:

Might be, but I would allow for 10 metric tonnes, to be safe.

The prop selection range is from 2,700 to 3000rpm so I'll have a bit of leeway, I'll run a few calculations at different weights and see what it throws up, can always have the pitch tweaked at a later lift.

 

[BrundallNavy]

We have a Nanni N65 with a 18x13. 3 blade propeller, she will easily do 10mph and has plenty of grunt to stop.  The down side is very little control when in neutral (no prop wash)   Hopefully next time she’s lifted we will modify the rudder as per BA.

She weighs close to 10 ton and is only 35ft. Is the engine an overkill in my opinion yes 43hp would be more than sufficient. 

[Vaughan]

 

Use of a snore hole.

You can just see the winch wire running along the ground under the port side. This runs out to a pulley sunk in the river, known as a deadman, and back to the aft snore hole.  The block and tackle on the stem is to check the boat and stop her running off down the slip on her own.

 

 

These photos were posed for an article in Motor Boat & Yachting, about 1952.  We didn't normally launch on a low tide!

[annv]

Hi Wooster my boat 44ftx11ft 6" has a displacement hull speed of just over 9 knots as worked out by a marine architect this is the max theoretical speed even with 150 hp engine it wont go faster if you have a planning hull then you would go faster as you would slide/float over the water rather then push the water aside as a displacement hull does. there is a optimum prop size  on the broads displacement hull is approx 17 inch dia and 13inch pitch powered by a 45 to 60 hp engine.you should be able to achieve the max RPM of the engine when flat out if sized correctly. often hire boats are sized with a larger/coarser pitch to stop the engine being over revved causing engine damage. you would get more speed with a smaller engine if you had a narrow hull width but still the hull speed would apply. we wont go into navy Destroyers as this gets very complicated . John

[Malanka]

Loving this thread.

As some may know we have had issues with drive plates and so on😁😩. That said talk of 2000rpm make me smile, as Malanka can lift her skirts when she wants and she easily reaches her waterline length boatspeed. Usually showing roughly 1300rpm flat out before we get cavitation and lose speed.

4mph is approx 450/550 rpm depending on winter or summer lol. 
 

She weighs a lot, her original weight stamp is still there at 9 tons and several tons have been added since then ( saddle water tanks, huge diesel tank, two black water tanks and the biggest addition of all is the massive 3.8L BMC commander engine. Originally 79hp but less now although a lot nearer since the flooding incident where over 10l of water was flushed out lol. It took seven flushes to get it all. 
Ask Doug what she feels like to helm all I can say is that on tickover you can feel the prop turning and she will turn in her own length when hard over, which I will demonstrate for the disbelievers when she again has a wet bottom, or even a bottom to get wet… lol 😂 

She is also incredibly thrifty with diesel we usually cruise two full weeks between fills up. All we need now is to get her planks in and repainted etc, gnawing my arm off to get afloat here…

[FlyingFortress]

Blimey

2 whole weeks.

That's some fuel economy.

Bit like my V8 car.

Boat does a LOT more.

[Malanka]

Lowest economy I ever got in the SVR was something like 40l per 100km, however I was doing 160mph + down the A5 in Germany, Ohne Geschwindigkeit controlle naturlich.

[wooster]

Thank you all for this thread. It's been interesting for me.

I guess the fact taht my diesels don't have turbos is a good thing. I tend to run on one engine alternately when I'm out and about which is economical. It's really handy to have both for manouevering though and also if we're pressing onwards against a tide or through Breydon.

Alas, we're selling our boat though. She's lovely, handles well and in great condition all around and I love her, but we're looking for something that will allow us to bring our families on for a week now and again and sadly our lovely boat is really ideal for the two of us or a family with two kids. It's not great as I've spent a fortune on her getting her improved and now she's just right we decide to sell.......

[FlyingFortress]

On 18/05/2022 at 22:46, Malanka said:

Lowest economy I ever got in the SVR was something like 40l per 100km, however I was doing 160mph + down the A5 in Germany, Ohne Geschwindigkeit controlle naturlich.

Think my V8 is restricted to 155 but as never taken it to Germany have never had the opportunity.

The V8 is a downsize . I lost 4 cylinders and 1.1 LTRs of displacement. Economy is now around 28ish to the gallon as opposed to around 20ish for the big un . Although 6 gears now as opposed to 3. Neither car turbo/ super charged. Don't understand these new fangled ltr per 100kms measurements as we don't measure distance in Kms here in the UK even though it's been many years since we bought fuel in gallons 

Boat

40 hp Lister Which regularly gave 3 weeks cruising North and South and never got below half a tank so around 100ltrs used. Lower when hot weather , higher when cold due to more use of the Diesel heating.

4 mph at 900rpm and 1300 at 6 mph. Never thought it was a slouch doing 8 mph across Breydon maxed out at 1950rpm obviously restricted. Slack water.

I just hope my decision to replace it with a Nanni does not come and bite me in the bum as my last boat had a Nanni and was nowhere near as economical.

[WherryNice]

I think 40l per 100km is about 7mpg if I have worked it out correctly. Tbh doesn't seem that bad for the speed. My V8 Discovery used to average 12mpg......

[Bikertov]

On 18/05/2022 at 22:46, Malanka said:

Lowest economy I ever got in the SVR was something like 40l per 100km, however I was doing 160mph + down the A5 in Germany, Ohne Geschwindigkeit controlle naturlich.

I managed about 165mph in Germany a few years back, on my big European bike tour.

Frankly, I was concentrating on the road too much to try and work out my fuel consumption 

[FlyingFortress]

Could get the V12 and can get the V8 into single figures quite easily.

The figures I was quoting were total average straight from the trip computer. Like I said don't go on unrestricted roads so never had a chance to go nutty for extended periods. 

 

[Malanka]

The max I ever did was 178 with Fiona in the car. I never went that fast just me as it didn’t balance correctly 

Theoretically she would do 195mph, however it was much more fun bouncing Porsche 911 turbos, and any BMW 7 series. The supercharger was amazing, thing whined like a banshee over 160mph. 575bhp from 5 L V 8 lump aluminium all over the shop and composite material panels, wheel arch vents that actually vented the wheel arch over pressure. She was 2.5 years of middle aged madness.