Life aboard a Little Harbor 44

[Panope]

Torque = HP x 5252 / RPM. So if you have the HP a prop will absorb, you have the torque.

Yes, exactly.

We should be looking at the Horsepower Propeller curve only.

....and ignore all published MAX curves.

There have been numerous posts in this thread that have advised consulting MAX torque curves. These posts are meaningless since we know that Alaris has a non-controllable propeller.

 

[bmiller]

This could be it's own thread just discussing props/engines.

Much has been said about exhaust temp. How do you determine a normal exhaust temp for a particular engine/prop/install?

 

[Israel Hands]

There is no way I'm listening to an engine running at 3600 rpm when I can get the speed I want at 2200 rpm. The fuel burn rate is good.

Will I wear my engine out faster? Most likely not and I don't care what people say. Do gen sets run at max rpm? Of course not, they run at 1500 rpm (4 pole 50 Hz) and the engines live a long happy life at that.

Marine diesels die of neglect at likely 50X the rate they do from premature wear running under some calculated optimal rpm.

^^ This.

 

[Howler]

The gearbox lever is your friend. So is propwash over the rudder, as well as propwalk.

Propwash is nice, but... I've been on a boat with the prop shaft off center and stuck out at a weird angle, (the two seem to balance each other, and the boat goes straight ahead under power without too much fight) but the prop is next to the rudder instead of in front of it. I've also encountered catamarans with saildrives astern of the rudders.

 

[accnick]

Propwash is nice, but... I've been on a boat with the prop shaft off center and stuck out at a weird angle, (the two seem to balance each other, and the boat goes straight ahead under power without too much fight) but the prop is next to the rudder instead of in front of it. I've also encountered catamarans with saildrives astern of the rudders.

My old yawl had the prop shaft offset to port, just forward of the rudder Steering under power was challenging.

My current boat has a huge prop right in front of the rudder. Handling under power is really good. It had better be, since we have no sails.

 

[Panope]

I can't (don't want to) reach full engine rpm with my prop pitch.

Don't care. All it means to me is, I have a lot more engine than I actually need.

There is no way I'm listening to an engine running at 3600 rpm when I can get the speed I want at 2200 rpm. The fuel burn rate is good.

OK I could back the pitch off a lot or fit a smaller prop. Then I'd make more noise likely burn more fuel and get the same speed. Not going to happen.

5 knots at 1600 rpm, 7.5 knots at 2200 rpm and the stern has squatted a good 200mm at that speed. Might get to 8.5 if I really pushed it. And wanted to burn 4X or more the fuel.

Will I wear my engine out faster? Most likely not and I don't care what people say. Do gen sets run at max rpm? Of course not, they run at 1500 rpm (4 pole 50 Hz) and the engines live a long happy life at that.

Marine diesels die of neglect at likely 50X the rate they do from premature wear running under some calculated optimal rpm.

FKT

FKT,

I have spent the last day and half trying to find a correlation between the post of mine that you quoted, and your response.

Near as I can tell, you interpreted what I wrote as me advocating for operating an engine at a particular speed. This is not the case. I was saying something entirely different.

.......but since you brought it up......

It appears that we are in perfect agreement about operating our diesel engines at low speeds.

I sometimes run mine as low as 1800 (red line is 3800). I do run it hard for a few minutes every couple hours too blow the snot out (just like the book says) but I never see any snot - or more than a tinge smoke.

My normal rpm is 2500 or about 25% power (I too have a fairly largish engine) and get 6.2 knots. I have operated at this power setting for 700+ hours with no carbon buildup in the exhaust elbow.

I have used 3000 rpm when trying to maintain decent boat speed when bashing into 25+ knots.

Full steam with boat running free gets 3700 rpm (I am slightly over propped). Never use it. Could be a life saver in an emergency.

Full steam with zero boat speed gets 3400. Used for pulling anchors only.

I once experimented powering directly into 40kts with a 4 foot chop. I could maintain close to 4 knots but was uncomfortable. No green water aboard, but the spray coming off the bows was memorable.

Steve

 

[Fah Kiew Tu]

FKT,

I have spent the last day and half trying to find a correlation between the post of mine that you quoted, and your response.

Near as I can tell, you interpreted what I wrote as me advocating for operating an engine at a particular speed. This is not the case. I was saying something entirely different.

.......but since you brought it up......

It appears that we are in perfect agreement about operating our diesel engines at low speeds.

I sometimes run mine as low as 1800 (red line is 3800). I do run it hard for a few minutes every couple hours too blow the snot out (just like the book says) but I never see any snot - or more than a tinge smoke.

My normal rpm is 2500 or about 25% power (I too have a fairly largish engine) and get 6.2 knots. I have operated at this power setting for 700+ hours with no carbon buildup in the exhaust elbow.

I have used 3000 rpm when trying to maintain decent boat speed when bashing into 25+ knots.

Full steam with boat running free gets 3700 rpm (I am slightly over propped). Never use it. Could be a life saver in an emergency.

Full steam with zero boat speed gets 3400. Used for pulling anchors only.

I once experimented powering directly into 40kts with a 4 foot chop. I could maintain close to 4 knots but was uncomfortable. No green water aboard, but the spray coming off the bows was memorable.

Steve

All good, we're in agreement in fact. Sometimes quoting gets a bit weird, could be me fucking it up, could be the software (as a sometime s/ware developer I figure you can't go wrong blaming code bugs, they're always there).

We operate our boats similarly too. I've got a Bukh DV36 engine with 3:1 reduction box and a 22" Autostream prop. That combo can push my boat into pretty much anything I want to tackle at 4 knots dead on the nose, engine happy with oil and water temps sitting on 70C and dead stable. One day I'll fit an EGT pyrometer just to see what's happening. As you say it can get a bit uncomfortable and a lot of flying spray.

Mostly I do 5-6 knots at a bit under 2000 rpm, if I run the speed up to 7.5 knots the fuel burn doubles and the boat is digging a big hole in the water. MAYBE I could push to 8.5 but what's the point. I do run at 7.5 every so often to give the engine a bit of a workout but the noise pisses me off so 30 mins is usually my tolerance limit. Crossing the ferry tracks is the main time I do this.

I could reduce the prop pitch but so far I've seen no reason to bother.

FKT

 

[Howler]

My old yawl had the prop shaft offset to port, just forward of the rudder Steering under power was challenging.

My current boat has a huge prop right in front of the rudder. Handling under power is really good. It had better be, since we have no sails.

View attachment 569819

Left-hand screw, like a Maine lobster boat?

 

[accnick]

Left-hand screw, like a Maine lobster boat?

Well, yes, since it is a Maine-built lobster boat under all the fancy stuff. The condescending term is "lobster yacht", but the politically-correct term is "downeast cruiser".

This hull is a Ralph Ellis design for Lee Wilbur, so intended to be built out either for work or pleasure. "Work" in this case usually means sportfishing rather than lobstering, however. Wilbur is a bit of a fancy builder for a purely commercial boat.

Like most lobster boats, it is grossly overpowered for the type of hull. Lobstermen love to put big engines in their workboats, although the high price of diesel fuel, plus the low landed price for lobster last year, meant a lot of boats cut back on fishing days.

 

[Alaris]

Alternator is indeed no good. Head install is a slow process. Haven’t had time to be at the boat much this week.

 

[Alaris]

The culprit for my NMEA2000 woes: a bad splitter/tee/whatever you call this. I replaced it with four tees and everything works fine.

 

[Sail4beer]

I was wondering how you could have trouble after being so thorough!

 

[mckenzie.keith]

View attachment 570729
The culprit for my NMEA2000 woes: a bad splitter/tee/whatever you call this. I replaced it with four tees and everything works fine.

Make sure you widlarize that bad splitter/tee thing.

 

[Alaris]

We have a head! Not yet wired up but all plumbing is complete except drilling the hole for the holding tank vent. It’s not centered because I’m left handed and after a lifetime of banging my elbow when on the toilet, I made sure there’s enough room on my boat.

West has a dock line sale going on so I replaced the hodge podge of frayed lines that came with the boat. Amazing what a difference that makes for the appearance at the dock.

Reconnected the water heater after investigating where the bypass went to… it works but the P.O. didn’t use it.

Plans in place to add an outlet for the eventual TV on bulkhead setup.

Also ordered V-berth mattress covers and sheets plus some rugs.

I think that’s it for today.

 

[Alaris]

Currently in varnishing hell. Trying to get a coat that doesn’t have dust in it.

I miss electrical work

 

[Zonker]

You need one of these. Keeps the dust out. Order the XXL size for your size of boat.

 

[eliboat]

If it’s only a little bit of dust, you won’t notice it in a month. If it’s insane… sand it flat and recoat. You can also buff it out if you’re inclined. The third option is to make it a matte finish, which looks nice on interiors anyways

 

[jwaldron]

Varnish dust nibs can be very effectively rubbed out with brown paper bag/brown butcher paper. Will leave gloss (largely) unchanged. Will rid of vast majority of dust bits. Easy if used with a sanding block.

 

[Howler]

Currently in varnishing hell. Trying to get a coat that doesn’t have dust in it.

I miss electrical work

Consider closing up the joint and running an air filter. Initially, the air filter creates air movement, which stirs up the dust and makes things worse, so what you might do is first vacuum up, then start the air filter, then thrash a towel or broom around all over the place to stir up the existing dust, and then walk away for a couple of hours to let the air filter capture the dust that's in the air, and then come back and varnish.
If you get a filter that combines carbon with HEPA, the fumes from the varnish will rapidly use up the carbon filter. Plain HEPA is probably what you want.

The Best Air Purifier

Clear the air—and maybe even improve your health—with a dedicated filter for any room in your home.

www.nytimes.com

I have an older one that looks like a fan with a couple of ring-shaped pleated paper air filters that look like they might fit a truck.

 

[Wess]

View attachment 568616 View attachment 568617

She looks a lot better in the water.

Nice; congrats!!

Fun catching up with this thread. Really cool project. Where did you end up location wise? Are you living aboard this winter?