Designing & Building Hammerhead

[dannc]

First rendering is in! Still a beta-model, so some of the detailing still lacks or needs a bit of extra love. But overall, I think it's a looker!

Regards, Edwin.

Very pretty. Amazing that we can make images that look like a photograph.

So where does the anchor, err mooring gear, go? Straight off the bow or of the port side?

Later,
Dan

 

[Salty Pelican]

Thanks!

Not in the rendering yet, but it will be straight of the bow. With a ... pulley system to push it forward and outward.

Odin.

 

[Salty Pelican]

We wanted a U-shaped galley, that hugs and holds the person cooking. But the original design we made, came with compromises. Not all cupboards were easily accessible, the galley could host only one person, we'd need to go for a smaller oven and a two-burner stove.

Until our NA's interior designer came in, that is. He proposed a new design. A parallel kitchen instead of a U-shaped one. Now all cupboards are easily accessible. And we can add a full size stove top and oven!

The pictures underneath show the old situation and the new proposal. We really like the new version!

Regards, Edwin & Veronika.

 

[Salty Pelican]

The red square in the second picture in the post above will see an additional locker or cupboard that'll use space in the ship's structure (hope that makes sense, English not being my mother tongue). Size is yet to be determined, but here's the idea (additional storage in red):

 

[Salty Pelican]

... I foresee a secret likker cabinet!

Regards, Edwin.

 

[dannc]

Corners in a kitchen or galley are difficult design issue.

Another idea is to have shallow cabinets at the end of the U that do not have much depth. 12inch/305mm deep cabinets can store quite a bit canned and dry goods. The shallow depth of the cabinets make it easy to find things too. 6-8 inch/150ish depths work as well. Less space/depth for storage but easy to find what is stored.

Since the shallow cabinet is at the end of the U, it can take up the entire height at the end of the U.

Later,
Dan

 

[Salty Pelican]

I guess so. Thanks for sharing!

Regards, Edwin.
(wife will chime in shortly)

 

[Benno]

Here is more on the anchor and chain topic. We had a 40kg original Bugel anchor from Germany on 250 ft. 3/8 HT chain on our Diesel Duck 41 (16 long tons). The Bugel anchor is the father of all roll bar anchors. We actually met Peter Smith of Rocna in Ushuaia, Argentina on the Beagle Channel just north of Cape Horn and had some great discussions. In all the 8 years of cruising with DD’s roll bar anchor we never dragged. We mostly anchored out and hardly spent time in a marina. Hey, in Patagonia there is no village for almost 1000 miles is the saying. The secret is to set the anchor with a scope of one to seven or eight. After it sets, pull it in, gear in reverse and with all what your engine can give you and then you take some slack out of the chain that so that you will not be wandering in no wind condition all over the anchor ground. Only in a strong wind forecast you smartly pay out more chain again.
The Bugel anchor we had flown into Canada from Germany several years ago. On my next boat I will hang a Rocna

 

[dannc]

Hopefully, this drawing make my previous post more understandable.

The cabinet by the sink has storage but it comes at the "cost" of easy access to the sink, the base cabinet under the sink, and the base cabinet next to the hull. I really wanted a cabinet at the other end of the galley but one has to balance out the cook top and work area next to the cook top.

The base cabinet next to the hull would have to have a very small drawer to fit the space as well.

Later,
Dan

 

[Salty Pelican]

Thanks Benno for sharing your ideas and experiences. Dan, what you say makes total sense. Short cabinet at the end of the U.

Regards, Edwin.

 

[Hippocampus]

I agree form follows function renders clean, sweet lines

 

[Salty Pelican]

Thanks! Here's another rendering.

Regards, Edwin & Veronika.

 

[Benno]

Good-looking boat and the drawing of your u-shape galley look great. It is a functioning set up for your gourmet cook. I am sure Veronika will be happy. We had a similar set up in our DD. You mentioned the space under the sink, were you are planning of adding a UV light in the cold-water circuit at the galley faucet to kill bacteria in the water. Sometimes when taking on water in marinas in strange places it could happen that it is contaminated. Like the saying in Mexico you could get “Montezuma’s Revenge”, a not so fine diarrhea. In general we used our 800 gal a day reverse osmosis system while the generator was running to avoid this problem. You probably will do this too I presume.
Best Regards, Benno

 

[Scooby5959]

Exactly what I was thinking

You are correct, that is not the case at all. Unlike a gas engine a Diesel engine matches the load with fuel real time to maintain rpm, at least up to the maximum rated hp for the given rpm it is running. If on a hp/rpm graph it says at 1800rpm it can make say 150hp but the load required is say only 100hp than you will only be making 100hp and burning the fuel required to make100hp. The difference on fuel burn between a Diesel engine running 1800rpm and 1200 rpm while the load on the engine is requiring say 60hp is negligible. 60hp requires virtually the same amount of fuel to make almost regardless of rpm, cubic displacement of engine or number of cylinders. The biggest fuel burn difference % would be between same hp engines being number of cylinders though. As number of cylinders goes down cubic displacement needs to go up to maintain reliability though. Inline 6 cylinder engines are the most balanced and by far the smoothest running and longest lived engines so I’m am always partial to an In-line6 compared to a v8 or inline 4. I used to do the penny test after a rebuild when growing up rebuilding old Detroit’s and 855 big cam Cummins. Which is after the rebuild place a penny on the valve cover and start the engine up. If the penny vibrates at all while running the engine up to max rpm you probobly did the rebuild wrong. No 4 cylinder gas or diesel I’ve ever seen can pass that test, most healthy inline 6 can. The fuel burn difference between a 300hp engine and a 150hp engine running on the same boat at the same weight at the same speed of say 10.5kts will be virtually identical. And on those identical boats no matter the rpm or hp of the engine both boats will require the same amount of hp to move the boat through the water at a same given speed. I’d be very surprised if it was more than 2% difference in fuel burn for the two different engines at the same speed. the advantage of the higher hp boat is it will of course go faster at of course a higher fuel burn when you decide to do that, also it would be a more reliable engine.. Also the slower a propeller spins the less slip there is in the water so a larger propeller with higher pitch that would come with a larger engine option run at a slower rpm than maximum rpm settings comes close to offsetting wherever inefficiency’s comes with going with a larger hp engine. It’s not exact but close enough that I wouldn’t possibly underpower the engine to try to grasp some magical efficiency while possibly under powering the boat. The boat you are looking at building is very similar to the dashew fpb 64 in both weight and length. I do not think you will make a more efficient hull design than a seasoned marine engineer that has been chasing efficiency for what 30+ years now, and has proven his ideas by making some of the fastest and most efficient ocean going cruising vessels to ever be sold. Maybe if you went without stabilization or compromised on hull thickness the shave weight but efficiency of a monohull is pretty explored science already. And sounding like fully loaded you will be very similar weight and length of the fpb 64 and they power there boat with a 236hp inline 6 jd. And the performance numbers you are looking for are almost identical so.... I don’t agree with everything system wise the dashews do but they make one of the most efficient world capable cruisers that have ever been put on the water while still maintaining amazing safety margins. I absolutely understand chasing ideas you want to confirm and wholly support your decision whatever that may be for the little that accounts for and am excited to see the results of your boat it being one of the more interesting new builds I’ve seen but making the decision from an informed position greatly makes making certain decisions easier and sometimes rules out previous conclusions. At the end of the day it’s your money your decision, and if you get an engine and it doesn’t meet the expectations you are wanting in both efficiency or speed that can be a very expensive mistake if you change later. How dissipointed would you be if your max speed ends up being 9.5-10kts and cruise speed is 8-9kts. Because that’s the downside of possibly under powering the boat. If your ok with that than go for it and you may end up being right. Honestly I’d call or message the dashews and ask them what they would think about installing that engine with that hp rating in a boat similar to there. Hell they may confirm your hypothesis on proper engine for your boat with your having to gamble and you could go with the 4045 comfortably without any question it’s the right motor.

Another way of saying it , There is a given amount of energy in fuel oil , if both engines are efficient at unlocking that energy ,they will consume pretty much the identical amount of fuel given the same load,Two more things and then I’ll go away hope I’m not bothering you, I would prop your boat to match your cruising speed whatever RPM the engine turns to produce the power you need is where you should prop your boat that way it is most efficient at that RPM and at that horsepower requirement, I believe that most displacement Boat are propped wrong,My opinion but I’m sticking to it, last thing I don’t believe turbos belong on a boat engine, I could explain why but it would take me a while , turbos are much like propellers they’re designed to run at the upper end of your power band , Where they produce most of their boost ,not necessarily where it is needed , also they can fail sometimes catastrophically , taking your engine with it , not something you want to happen in the middle of the ocean just my opinion

 

[Scooby5959]

Sorry here is another way of saying it ,turbos are used to force more horsepower out of an engine ,I would prefer that engine to produce the horsepower needed ,naturally so to speak

 

[Salty Pelican]

Scooby, thanks for sharing. Our boat will be optimized for her cruising speed of 10 knots. Prop included, engine included. I think that what you refer to is that most boats are optimized, propwise, from the topspeed perspective, thus creating a less than optimal situation at actual cruising speed. That's one of the things we'll do differently.

Benno, thanks for the kudo's on the galley. Yes, very happy with the new design. Great addition on treating drinking water. Haven't had Montezuma's Revenge yet, but I have experienced the Delhi Belly after a trip to India. Not fun.

Regards, Edwin.

 

[Mako]

@JMarsh that’s a good write-up except you didn’t take into account that an engine’s efficiency is not consistent throughout its power band.

Popular language is that a typical marine engine produces 20 hp/gal-hr. But look at the specific fuel consumption curves. In reality, a high hp engine may produce 12 hp/gal-hr when running at 15-20% load, could peak (19-20hp/g-h) at 50%, then become a slob again at high rpms.

So when you read “my 300hp engine sips fuel burning only 3gph at trawler speed” in reality it is a fuel hog. A guy who spends his whole life slow cruising, installing a 100hp engine, might obtain 20% better efficiency. That’s an incredible improvement for a word cruiser, but perhaps negligible for a typical dock queen.

I think choosing an engine is full of compromises unless one has the discipline to design for a narrow cruise speed band.

Tier4 electronically controlled engines will do slightly better than mechanicals at that low load value, but generally have poorer efficiency at higher loads. I haven’t checked but would be surprised if the JD peaks at more than 19.3

 

[Scooby5959]

Another way to say what I’m trying to explain

Scooby, thanks for sharing. Our boat will be optimized for her cruising speed of 10 knots. Prop included, engine included. I think that what you refer to is that most boats are optimized, propwise, from the topspeed perspective, thus creating a less than optimal situation at actual cruising speed. That's one of the things we'll do differently.

Benno, thanks for the kudo's on the galley. Yes, very happy with the new design. Great addition on treating drinking water. Haven't had Montezuma's Revenge yet, but I have experienced the Delhi Belly after a trip to India. Not fun.

Regards, Edwin.

Most boats are propped for their maximum rpm some people call that wot , it’s important to you have a 10 knot cruise , but that most likely won’t be at full throttle , so the engine/boat should be propped where you’re going to be cruising , in other words were ever the throttle is going to live

 

[Salty Pelican]

Yes, I agree. 1800 to 1850 rpm. That's the sweet spot.

Regards, Edwin.

 

[Salty Pelican]

Cockpit

Here's an initial cockpit design rendering.

Regards, Edwin & Veronika.

 

[Benno]

Matching prop pitch to engine rpm (gearbox rpm) to gain a economically boat speed is truly easy when having a CPP Propellor System and the right engine horse power. I would say 5 hp per long ton and a CPP Propellor System like the one from West Mekan, Norway. A CPP is not overly expensive and will save you fuel in the long run too. I had one on our DD and many times changed the pitch while running the boat to match the propellor to the sea state or going up canals, rivers with current etc. With a little move of a finger on a joystick at the dash board you solve all the pitch problem. The system is foul proofed and in all the eight years of owning our DD41 it never had a problem. Going up the Orinoco River in Venezuela or rounding Cape Horn in a shitty sea or just plowing down the Intracoastal Waterway on the east coast of the USA we always had the best power and pitch on the propellor. Something to think about. Best regards, Benno

 

[Hippocampus]

The early Artnauticas came with a variable pitch prop. Tune to exhaust temp you’re most efficient. Neither VOG, rpm nor speed through the water match with load. It’s load (how much torque not just power) that correlates best with what pitch you should have from the little I understand. If you’re running 90% of the time with a specific loading pitching for that and avoiding the expense and complexity of a variable pitch makes great sense. If your usage will vary widely (European canals then high lat long passages) perhaps you may want to investigate variable pitch. David Gerr wrote about props. Worth a read. Don’t know if modern common rail makes some of this irrelevant. Would discuss with experts.

 

[Salty Pelican]

For now we are choosing to optimize for the 10 knots cruising speed and indeed expect to stay at the associated load for over 90% of the time. So no variable pitch. Reducing complexity where possible.

Regards, Edwin.

 

[Benno]

Hippocampus you are correct, watching the exhaust temperature on a pyrometer is important in setting a CPP system. You are right Edwin, a boat can do easy without a CCP system, the cost was triple of the standard shaft and the propellor as I recall it. You are going to have a gorgeous yacht the way I can see it. Best regards, Benno

 

[twistedtree]

For now we are choosing to optimize for the 10 knots cruising speed and indeed expect to stay at the associated load for over 90% of the time. So no variable pitch. Reducing complexity where possible.

Regards, Edwin.

How do you know what engine RPM/load is most efficient at your desired 10 kts? It seems you would need a full fuel map for the engine to determine that. Is that available for the Deere engine you have selected? I haven't seen one, but perhaps just haven't looked hard enough. Nearly all of the BSFC plots that I have seen show BSFC along the full-power curve, or possibly along the prop-load curve. I'd be really interested to see a full BSFC map for a modern engine. I know the full-power curve for my engine is remarkably flat at any RPM you would actually run it.

 

[Scooby5959]

What if I were to tell you you’re looking at this all wrong “bold statement “I can back it up ,I can show you how you can accomplish your goals while saving at least 1/3 on your fuel burn, you should not Spec an engine Based on horsepower ,rather based on the torque curve ,this would require a much larger engine and a controllable pitch propeller, I am so confident in this statement that I am willing to put some skin in the game “!!! what say you You would not only save a tremendous amount of fuel ,it will also double your engine life and have a boat that was much more pleasant to be in, quiet smooth fuel-efficient,Anybody else interested ,y’all think that I just have a big head and I’m a blowhard ,pony up anybody

 

[twistedtree]

What if I were to tell you you’re looking at this all wrong “bold statement “I can back it up ,I can show you how you can accomplish your goals while saving at least 1/3 on your fuel burn, you should not Spec an engine Based on horsepower ,rather based on the torque curve ,this would require a much larger engine and a controllable pitch propeller, I am so confident in this statement that I am willing to put some skin in the game “!!! what say you You would not only save a tremendous amount of fuel ,it will also double your engine life and have a boat that was much more pleasant to be in, quiet smooth fuel-efficient,Anybody else interested ,y’all think that I just have a big head and I’m a blowhard ,pony up anybody

Please describe, ideally with actual data to quantify the differences. I've certainly heard the arguments, and don't disbelieve. I've just never seen any real quantification of the savings, including how it varies for different types/generations of diesels. What's good for a Gardner, Detroit 2 cycle, Lehman, modern unit injector, or HPCI may be different.

 

[Scooby5959]

I’m sure this would work with pretty much any modern engine ,with the exception Of an engine that has a particulate filter and uses exhaust fluid ,those Engines have to run Within Certain parameters in order to make the pollution crap work ,I hear they’re requiring those in boats in California ,but I’m not certain, I don’t know how you could possibly put that in a boat ,but that’s what I’ve heard ,There are three ways I could demonstrate this, The first would be to use manufacturers Published power Graph,The second would be to put the engines on a Dino and the third would be to actually put the engines in a boat first one engine then remove it and put the other engine in and compare notes that obviously would be very expensive ,I personally couldn’t afford to do the dino thing either ,so I have to use manufactures published numbers they do guarantee these numbers however ,so hopefully they’re accurate ,I know my theory holds water with my experience with semi truck engines ,I always got better fuel economy with a higher horsepower engines ,so I decided to look up the numbers for Marine engines ,and was astounded with what I found ,even better than big truck numbers ,I’m still waiting for somebody to put some skin in the game And don’t forget this requires a Cpp propeller ,I’m pretty sure nobody really cares what I have to say ,I was scolded by the administrators for being too uppity ,I didn’t wanna argue with them ,when my numbers prove correct ,I expect an apology,

 

[twistedtree]

I’m sure this would work with pretty much any modern engine ,with the exception Of an engine that has a particulate filter and uses exhaust fluid ,those Engines have to run Within Certain parameters in order to make the pollution crap work ,I hear they’re requiring those in boats in California ,but I’m not certain, I don’t know how you could possibly put that in a boat ,but that’s what I’ve heard ,There are three ways I could demonstrate this, The first would be to use manufacturers Published power Graph,The second would be to put the engines on a Dino and the third would be to actually put the engines in a boat first one engine then remove it and put the other engine in and compare notes that obviously would be very expensive ,I personally couldn’t afford to do the dino thing either ,so I have to use manufactures published numbers they do guarantee these numbers however ,so hopefully they’re accurate ,I know my theory holds water with my experience with semi truck engines ,I always got better fuel economy with a higher horsepower engines ,so I decided to look up the numbers for Marine engines ,and was astounded with what I found ,even better than big truck numbers ,I’m still waiting for somebody to put some skin in the game And don’t forget this requires a Cpp propeller ,I’m pretty sure nobody really cares what I have to say ,I was scolded by the administrators for being too uppity ,I didn’t wanna argue with them ,when my numbers prove correct ,I expect an apology,

Just to be clear, I'm not saying you are wrong. I'm just looking to quantify because I've never seen it done credibly.


Attached are spec sheets for two Deere marine diesels, one 9L and the other 13L. Let's pick the M2 rated version of each. You pick whatever power level you want for our hypothetical boat, and we can compare between the two.


When people talk about propping for efficiency vs top end power, what they usually mean is this, referencing the performance graphs:


- Pick a HP point needed to drive the boat at some given speed.


- From the prop curve, you can see the engine RPM to get that HP.


- Now note that you can get 100hp out of the engine at lower RPM and high torque, limited only by the engine's max power curve.


- Then you can re-prop to pull the same 100hp at a lower rpm.


In theory this drives up efficiency, but actual numbers are elusive, at best.


One thing you can look at for each engine are the BSFC numbers across the RPM range for the prop curve. Comparing any RPMs that you might reasonably use, the BSFC doesn't vary by more than 2-3%. So that's the most you can gain my propping to a different RPM/torque power point.


Also, comparing the 9L and 13L engines are similar power outputs, with few exceptions their BSFC is within a percent or two of each other.

 

[Salty Pelican]

A boat that's powered to its top speed will see an equal number of engine hp and prop hp. Anything lower will see (usually huge) differences between the number of hp the engine puts out, and the (much lower) hp the prop puts in the water.

If you cruise at - say - 1800 rpm, instead of at the max 2,500 rpm, you can prop to optimize (equalize) for 1800 rpm. In such a way that - at that rpm - the prop performs best and has an equal engine hp and prop hp number.

Given prop losses at lower rpm can easily be 30%, potentially a 30% efficiency gain could be accomplished.

Regards, Edwin.