Designing & Building Hammerhead

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A couple of engine thoughts....


I'm not sure what regulations you are subject to with an EU build, but I suspect you will be constrained to an EPA/IMO emissions controlled engine. That precludes the use of older remans, or other favorite engines of days gone by. I remember discussing this with Wayne on Mobius, and they found a way around it to use their Gardner, but I think it blocks them from ever registering the boat in certain countries, or at least if the emissions compliance is ever inspected. But I think the engines you have been discussing are all US and EU certified, so probably a moot point.


I too like the idea of the Deere 6068, but it's minimum HP rating is higher than what you have been contemplating. Now that may be just fine, and perhaps even desirable, but I just point it out.


On emissions compliant engines, the keel-cooled variants are increasing dual keel cooler designs. I don't know about the 6068 specifically, nor the 4045 for that matter, but it's a complication for a keel cooled boat. That said, I think you are planning on sea water + heat exchanger cooled?


I personally don't think a CPP makes sense on a boat like this. They are typically used in two situations.


First is on much larger boats with engines that have a very narrow operating RPM range. You can't get enough speed control by varying rpm, so you add in the ability to vary pitch. It also provides the opportunity to eliminate the reversing gear since you can just reverse pitch. But this is not applicable to your boat.


The other situation is with a motor sailor where you have significant variation in the amount of power assist needed at any given speed through water. In this case the CPP gives you more flexibility to match boat speed, engine rpm, and the amount of assist power.


Your boat is just like every other small power boat in this respect, and I suspect you will get very little fuel economy advantage from a CPP. Yet you will be taking on a significant initial cost, and long term maintenance cost. I personally don't think the economy gain, if any, is a hair worth splitting.
 
JD has a 6068 M1 rated block that produces around 155 bhp. That should do it easily. Cruising at 10 knots at 95 to 100 bhp. 155 will take her to 11.5 top speed that we won't be looking for (and won't optimize for). Both the 4045 and 6068 are EU-certified. I always imagined direct cooling with sea water, but would love to hear any feedback from your experiences.

Addition: I mean indirect cooling with sea water via a heat exchanger.

Regards, Edwin.
 
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I think with an M1 rated engine, you want to plan on running around WOT for a decent percent of the time. That will probably be around 75% of that same engine's load if it were M4 rated. So I'd recommend being careful about oversizing AND having it rated for M1.

I'm looking at my JD Operator's Manual and it shows two 6068's:
6068AFM85 with an M1 rating of 172kW or 230 hp.
6068SFM85 with an M1 rating of 186kW or 249 hp.

I don't see the model with an M1 rating with 155 bhp - although if you can find one, I'd agree it should run forever with proper maintenance.
 
The JD 6068 is slightly longer and a little bit narrower than the 4045. Here is a birdview drawing. Anyone have some price indications that can help me prep talks with the importer here?

Regards, Edwin.
 

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I didn't catch any earlier discussion of horseshoe shaped tanks. I've not seen that in practice before. Will you have multiple tanks, or just the one?

I've always been hesitant to have a single tank, especially when refueling in the hinterlands where you may take on a bad load of fuel that could contaminate the entire system. I've never had this system, but I always thought multiple tanks with polishing and transfer system would be slick, so you could transfer all existing fuel over to one tank and then fill the now-empty tank from the questionable source.

In my application, I have two independent engines with their own tank and no transfer ability between the two tanks. That's sub-optimal, but I don't have any plans to change things. I could always add a transfer capability - but if I only had one tank, I'd put a lot of thought into my refueling procedure.
 
Hammerhead will have 5 tanks. The lay-out of the tanks is in a U- or horseshoe shape, Bkay.

Regards, Edwin.
 
Salty Pelican said:
Hammerhead will have 5 tanks. The lay-out of the tanks is in a U- or horseshoe shape, Bkay.

Regards, Edwin.
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Good call. Don't you love it when you are building a boat and people just assume they know more than you? Me either!

She'll be great! I hope you enjoy the journey!

Dave
 
Salty Pelican said:
Bkay, yes, agree completely, which is why the lower HP variant is what we need. A 230 bhp would not run at high enough load, when we normally use around 95 bhp during cruise.

Here's the engine I refer to:

https://www.deere.com/en/marine-engines/propulsion/powertech-6-8l-6068tfm50/

Regards, Edwin.
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If you need an EPA Tier 3 engine to import the boat into the US, I don't think that engine will work. It is an 6068TFM50. TFM means, T-Turbo, F-JD engine, and M-Marine. 50 is a non emissions regulated engine.

https://www.deere.com/assets/images...duct/r_Marine_Engine_Naming_Guide_877x493.jpg

I believe an 85 engine is needed to meet EPA Tier 3 or RDC II emissions standards. I don't see a 6068 engine under 230 HP that is EPA Tier 3 or RDC II rated. If meeting emissions requirements is required, there is a 4045AFM85 engine at 160 HP at M1.

Later,
Dan
 
Thanks for sharing. I'll check with the importer here on certifications.

Regards, Edwin.
 
Bkay said:
Ah, very good. I'm not sure why that one is not listed in my owner's manual. It may be newer or simply not available here.

Thanks.
Click to expand...

You manual is for EPA Tier 3 rated engines required for the US. The engine he is looking at would not meet EPA regulations in the US.

Later,
Dan
 
Salty Pelican said:
Thanks for sharing. I'll check with the importer here on certifications.

Regards, Edwin.
Click to expand...

My understanding is that if you want to import the boat back to the US, the engine needs to be EPA Tier III rated. The only way I know to escape that requirement is to do a home build.

A RCD II rated engine is needed for a boat imported into the EU. The EPA Tier III standard is cleaner than an RCD II engine but an RCD II rated engine is NOT clean enough to meet EPA regulations.

There are other emission requirements in the EU for the Rhine river and other inland waterways.

Later,
Dan
 
Salty Pelican said:
Bkay, yes, agree completely, which is why the lower HP variant is what we need. A 230 bhp would not run at high enough load, when we normally use around 95 bhp during cruise.

Here's the engine I refer to:

https://www.deere.com/en/marine-engines/propulsion/powertech-6-8l-6068tfm50/

Regards, Edwin.
Click to expand...


That would be excellent if it meets your environmental requirements. Unfortunately it won't fly in the US, and I was under the impression that EU requirements are at least as strict, if not more so. What standard do you need to meet?


It's one of the older design mechanically injected engines which will make a lot of people weak in the knees.
 
Edwin how much tankage of fuel and potable water are you planning on. 2000gallons of fuel will bump you up to a little over 14,000 lbs so a little Cush room on the upper end of the hp rating will allow you to stay right around the 90% on the throttles while maintaining the speed your looking for. Just to give you an idea based off of 2000 gallons of fuel
 

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How big is your alternator? Extra Large alternators can suck up to and some over 20+hp. What type of gears? Efficiency of drive line? How much does your skiff weigh? Stabilizers? They create drag. You running any hydraulics off of your motor? There are conversions for finding out exactly how much power accessories and driveline are robbing from your engine. How much home stuff are you bringing along. That cruising at 10kts at 95-100 hp to your wheel, you could really be using a full 150 hp of your engine depending on your accessory setup and extra weight aboard. Pounds equals hundreds of pounds equals tons very quickly when you start talking about moving what is essentially your home. Don’t underpower your boat, you will never get the speed you are looking at if you do and it will make you quite annoyed when that happens. To give you an idea, I’ve got a 42 foot aluminum trawler, weighs 18,000 dry. Between my 1,200 gallons of fuel and stuff I have put inside, as well as water I’m 30,500 last time I was hauled. Weight adds up fast on lightweight boats. But I’ve got 4000+Nm range so I can’t complains too much when it’s such a small boat. And anytime you are looking at a small displacement engine or a larger displacement both at the same hp rating alway go with the heavy steel. It will last a lot longer. That’s why sport fishing guys have 2-3000 hour tbo times because there engines are way too small physically to handle that type of power they are making. A commercial level 1500hp engine literally weighs 2-3 times more than what they are putting in the sport fishing boats. Most commercial boats go 20,000-40,000 hours between major overhauls. It’s the same for what your looking at. A 4bt at 180hp may last between 4-8,000 hours while a 6b at 180hp may last 30,000. A sub 200hp 6068 should last 30-40,000 hours with good maintenance. I’d add all the tankage to your boat weight wise and add 10% more for misc stuff you will accumulate over the years and aim for a top speed of 11 and find out what hp you need for that weight.
 
Also once you figure it out add all the accessories hp drain you plan on running as well to that final number at the end and that will tell you how much hp you should have on your main.
 
And you are looking for that hp mumber at your desired cruise speed, weight and accessories being driven for the m1 rating btw. m1-m4 is a lot of the time just max rpm settings. You can see here on the 6068 tfm75 the m1 rating is for 2400 rpm it can make 158hp. At That m1 rating can be run 24/7 365 with no issues and reach the desired commercial tbo. But that same engine can actueally be run at 2600 rpm making 201hp but can only be run like that at an m3 rating. Which would be for a maximum of 12 hours per day and the rest at a reduced m1 rating. You also have to match your wheel to your desired shaft speed and shaft rpm with all accessories running. Your wheel may only be asking for 100 hp at 2400rpm but the accessories and parasitic loss may actueally be asking for the full 150hp from the engine. if the wheel or accessories ask for more than the 150hp it will jump your egt levels and start dragging your engine down causing premature wear and possibly damage in the long term.
 

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Thanks for sharing. In touch with the Dutch JD importer, while our naval architect is looking into the required/preferred certifications.

I made an Excel-sheet to calculate how much power is used by the various appliances. That should help with alternator, battery, and generator selection. Based on four scenario's (at anker/sailing, cold/warm climate conditions), a first prediction estimates between 26 and 44 kWh electrical requirement per day.

With solar delivering 4 to 6 kWh and the alternator chiming in for 7 kWh, net daily additional electrical power is down to 15 to 38 kWh roughly. This first concept calculation, that definately needs more fine-tuning, asks for a daily generator use of 1.3 to 3.1 hours (12 kWh genset) per day. That translates to around 10 liters per day as an additional consumption of fuel.

Again, just some first calculations, but nothing frightening so far.

Regards, Edwin & Veronika.
 
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Regarding power production...

One of the differences between an LRC or FPB vs other boats is the amount of solar power panels on the boats. On the LRC 65, it is at least 5K watts. This is a game changer, especially compared to a sailboat where one is going to have to make some design choices to get around 1K watts.

With 5KW+ of solar panels, the boat we are planning will have surplus power 10 months of the years. LOTS of surplus power. There is so much power it is influencing fridge/freezer selection. The problem months would be in northern Europe in December and January, but even then, the Victron calculator says we might be able to produce the power needed via solar. It would be close though.

Cooling HVAC not included.

Having said that, it seems that some cooling could be done using power generated/stored by solar.

As mentioned by other posters, correctly loading the engine is important and one does need some HP overhead for sea state, wind, power production and/our hydraulics if used.

Voyaging Under Power by Bebee has a method for calculating needed engine HP that seems to be in the ball park for boats I have looked at and where I have the information to verify his formula.

I would prefer to not have twin engines but I want two ways to move the boat. I would prefer one engine and a decent sail plan but that has some design choices that are problematic as well.... <sigh>

An LRC-65, with twin engines, :rolleyes:, can have smaller HP engines, with alternators that can help provide the proper load. I have yet to find a definitive definition of what a proper load is on a modern diesel but I think I can come close with the right choices of alternators. Pretty sure I can get there but worry about the structural loading on the engine for belt driven alternators. Flip side, is I don't see the need to produce that much power from the engines due the solar power production, except for that pesky cooling requirement. :banghead:

Then there are PTO or hydraulic alternators/generators... Choice, choices, choices. :eek::D

We really do not want a generator, and with the possible exception of the need to cool the boat, I do not see the need due to the amount of solar that can be put on the boat along with twin engines running higher output alternators.

Twin engines also allows the boat to be dried out which is an interesting ability. Tis a bunch of design choices. Choices, choices, choices. :D:lol:

Later,
Dan
 
We'll have over 6 kWh of solar installed, Dan, on Hammerhead. Optionally more, if we also use the cockpit roof. We could go to 10 kWh that way.

In the power consumption I have calculated 3 kWh of cooling from an AC unit for 4 hours a day in warm climate conditions. It is part of the load that we need to cover with solar/electric engine/generator. No problem. I like my sleeping quarters a bit cooler, but only to fall asleep. No need for 24/7 airconditioning

I am thinking of replacing the engine alternators, since we'll install an electric engine that can be driven from the shaft (and it can drive the shaft). Alternators are very energy inefficient.

Generator will be used as back-up propulsion. Battery pack as the buffer in between.

On engine load, I think there are two schools of thought. The first one is aiming for a 70 to 80% load in terms of fuel usage. So if the max fuel consumption is 33 liters per hour, aim for an rpm that gives a fuel consumption of 20 to 25 liters per hour. The other school of thought says that a lower load is perfectly fine, but rev the engine up to above 80% load for 20 minutes every 24 hours. I have been running Salty Pelican according to the second interpretation.

Regards,
 
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I've been following with interest, and thinking of my earlier endorsement of the 4045.

I fully understand the optimization desire. But if it were me, I'd be thinking also of situations where I might want more power. Maybe a lot more.

Your 10 knot target is great. But I'd be asking the NA how much power is required to punch into a 45 knot headwind and associated seas at that speed. I'd also be asking about flank speed capabilities.

10 knots is 1.25 x square root waterline. Another few knots shouldn't be hard to accomodate, if only for emergencies.

That would probably lead me to consider M2 or M3 rated motors. That may seem heretical to some here, but I've studied the John Deere marine ratings carefully, and I just can't see the case for an M1 in any recreational boat, unless someone other than the owner is driving it.

I also can't imagine considering anything but a fully compliant new motor, especially in Europe.

The 6068 M3 rated at 300 hp gets my vote. I suspect that the fuel usage at 100 hp wouldn't be materially different between that and a 4045, and you can run it forever at that output.
 
Thanks Jeff for sharing your thoughts. Given its intended purpose, yes, it needs to be a new engine, with all the proper certification, which rules out the 158 bhp 6068. The 4045 AFM 85 at 160 bhp does comply.

A stronger engine is not an option. It would mean that - if we were to use the overpower occasionally - the whole propulsion system needs to be tweaked to facilitate those higher speeds ... and thus creating prop loss efficiency at the 10 knots cruising speed we seek, resulting in approximately 30 to 40% higher fuel consumption at that high cruising speed that we are designing for.

Also, applying fast displacement design elements allows Hammerhead to sail at that high cruising speed, relatively close to its theoretical displacement speed of 10.85 knots, with ease. If we'd want her to go quicker and seek semi-displacement speeds, using the proposed 300 bhp to push her to 14 knots, the emphasis of the underwater-ship would need to change. This would be less than optimal at the desired cruising speed, in terms of efficiency and boat handling. The stern section would need to be wider and sit "on" the water rather than "in" it, resulting in a sloppier handling at sub-semi-displacement speeds.

Also the speed gain would be minimal. 300 bhp would bring her to 14 knots, where the 4045 m1 at 160 bhp will bring her to 11.5 knots at half the fuel burn. The more we investigate, the more likely the 4045 becomes.

Regards, Edwin & Veronika.
 
To be clear, I wasn't suggesting optimizing the hull design for a higher speed. If the difference in fuel consumption between 10 knots with 300 hp available vs 10 knots with 160 hp available is 20-30% then I understand the decision fully. I'd be really surprised if that's the case, but am not an expert.
 
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.
 
Thanks for chiming in! I'll discuss with the NA to see if my assumption that a bigger engine, with the prop to take advantage of the higher speed potential, results in less efficiency at the 10 knot cruising speed we aim for, is correct or needs revision. We'll also go over the numbers again.

Dashew's FPB is significantly heavier than Hammerhead. She is higher above the water and additional bottom plating seems to be used to act as balast to compensate, explaining a lot of that weight difference.

Anyhow, to be continued!

Regards, Edwin & Veronika.
 
All right, just had our naval architect look at it and the numbers of the 160 bhp 4045 again and they are more than good enough for the intended cruising speed of 10 knots as well as the top speed of 11.5.

Going for a bigger engine would only unlock the additional speed potential, if we - as I expected - would redesign the aft underwater ship, resulting in more drag at 10 knots, increasing fuel consumption significantly and resulting in needing to add bigger fuel tanks, that would make the ship heavier, resulting in more fuel use, etc. Vicious circle, so a no go.

He also explained that, to obtain the 14 knots speed that goes with the 300 bhp engine option, the prop pitch would need to be augmented. This, again, results in a less efficient prop function at the intended fast cruising speed of 10 knots.

All in all, a bigger engine and a differently designed underwater ship might benefit a coastal cruiser, but not the long range expedition vessel we are looking for.

Thanks for your input and feedback. It allows to reconsider things, to rethink, and to change and adapt, or sometimes to get reaffirmed on previous decisions.

Regards, Edwin & Veronika.
 
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Awesome, that’s great they were able to really confirm that that motor will work out well and fits the bill perfectly for intended use. My oppinion for what it’s worth the jd 4045 is probobly the best sub 5liter inline 4 cylinder on the market so you should be happy with it if all the math is adding up. Once you start your sea trials I really want to hear your real world numbers on fuel burn, wet fully loaded weight and speeds you are obtaining. How soon until you plan on having the keel laid?
 
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