I have just been handed a boat design challenge

[mmd]

I know that most here are not interested in a.) fishing boats and b.) boats made of the Other Stuff, but I'll toss this out just to see if there is anybody with an interest:

So about two months ago I landed a new client - a start-up boat shop that is planning to cater to the local fishing boat market. They are looking to me to guide them through the maze of government regulations, do the technical bits such as scantlings calculations, tonnage measurement, and stability assessment - my 'bread & butter' jobs. Most boatshops hereabouts buy a stock hull from one of three or four shops that have a mold for a hull and modify it (lengthen, widen, raise the sheer, etc.) as the client wishes, either in-house or have the hull builder modify it to suit. The bare hull - with a few stringers, engine beds, and a couple of bulkheads installed - is then trucked or towed to the 'finisher' who builds the boat to the specifications laid out by the client. Most boats have bulkheads, decks and structure made of plywood and dimensional timber, which is 'glassed over. Not my favourite method of construction, but to use the common phrase hereabouts, "that's the way we always done it".

Last Friday, the principle of the company, his new client, and the hydraulics sub-contractor came out to see me at my home office to discuss a new project. They have given me a really nice challenge: The boat will be laid out in the usual configuration, and the hardware and machinery will be the tried-and-true stuff, but (and this is a BIG 'but') they have given me free rein to design the boat as I see fit to create a new, better type of boat. No wood structure (all foam-core 'glass), find new ways to make the boat mechanicals more efficient, etc. The primary directive is to do the same job as others of it's type, but see if we can make it more fuel-efficient, make the quality of the landed catch better, make it easier to work on the boat, etc.

Awesome. I have been wanting to do this for about ten years. It is going to look somewhat like this older design from a couple of years ago, 'cept betterer:

201705-030112 General Arrangement Rev 2.jpg

[Gib Etheridge]

Is it too fast for a Kort nozzle?

[mmd]

Is it too fast for a Kort nozzle?

No, but a nozzle is not really needed. Nozzles concentrate thrust, which is good for towing (towboats, seiners, draggers, etc.) but when free-running they add drag and don't increase speed. The boat - because of its form (basically has the streamlining of a construction brick) - will never see the far side of hull speed, despite multitudes of attempts by stuffing the hulls with ginormous horsepower. So, if we can hit ten knots, everybody will be happy. A knot more and we'll all be ecstatic.


Chris & Nick, I will keep you posted as I progress, with the caveat that I will not post anything sensitive to my builder or his client. Nothing will happen until October, as I have a planned ten-day vacation next week and three stability booklets to pump out before the end of the month. But please ask questions as I go along; I'm not good at maintaining a monologue.

[cstevens]

A dream job. Congratulations! I'm definitely interested. It may not be wood but I'd love to follow along as you work through it if you care to share the process.

[Peerie Maa]

^ Wot Chris said.

[Rich Jones]

I, for one, am fascinated with your designing posts no matter the material.
Looking forward to following this one.

[David G]

I, for one, am fascinated with your designing posts no matter the material.
Looking forward to following this one.

Precisely.

My favorite sort of job - when the client really wants you to excel and improve upon the SOP. Did they specify a budget - to help frame your thinking?

[Nicholas Scheuer]

Very interesting thread!

[Gib Etheridge]

Not arguing but isn't that precisely where a Kort nozzle is most advantageous, at less than 10 knots, heavily loaded?

[mmd]

Not arguing but isn't that precisely where a Kort nozzle is most advantageous, at less than 10 knots, heavily loaded?

Yes. But...

The boat is heavily loaded about six time a year. Not worth the twenty-five grand or so for a nozzle. I can make the stern apeture pretty much any size I want, so can have pretty much any size prop I want, so if I can achieve hull speed without the help of a nozzle, I cut construction costs. Every thing is a compromise...

I will, as a matter of course, look into a nozzle to see if it is advantageous, but I am predisposed to discount it.

[peter radclyffe]

good for you

[John B]

Heck yeah, sign me up.

[Gib Etheridge]

Perhaps it would be more cost efficient if the nozzle were to be the rudder as well thereby eliminating the need for the traditional rudder.

You realize of course that I know nought of which I speak, just trying to be helpful. I like coming up with ideas. Thanks for the opportunity.

[mmd]

Both of your ideas are good 'uns, Gib; just very, very expensive. I consider it a big win that I have convinced someone that a NACA-foil rudder is an improvement over a flat plate one.

Here's a bone to chew on, though: All of the local boats cool their engines via a closed-loop cooling system consisting of a loop of galvanized pipe running along the bottom of the hull. This works, for sure, but it adds a lot of drag to the hull. So I am considering either a recessed Fernstrum Gridcooler for each engine (prime propulsion and generator), or a seabay with WEKA boxcoolers. The latter has some non-cooling-related advantages, if the price is right and the engine room can be configured to place them. Consider & discuss - I'll run off and do some work and check back in a while.

[cstevens]

Interesting. The WEKA boxcooler looks like it could be more problematic in service. In particular I wonder about issues with cooling water flow at low speeds. Is it proven for fishing applications? Also the gridcooler option seems like it would lead to a more flexible design. The recesses for the gridcoolers might be less intrusive and easier to work around if the machinery spec changes than the seabay for the boxcoolers? I could easily see the yard wanting to increase the fuel tank size or something, and having to reenginer the seabay location to make it work. Or some other similar change.

[David Cockey]

Douglas Read of Maine Maritime Academy has been working on a redesign of the Maine lobster boat using a trimaran hull to improve efficiency. One conclusion he reached early on was the boat would need to look like a traditional lobster boat above the waterline if it was to be accepted by the lobstermen. Read has projected a 30% improvement in efficiency but lower top speed capabilities. Progress has been somewhat sporadic. A 21' demonstration hull was built several years ago.
https://coastalfisheries.org/collabo...-lobster-boat/
https://www.pressherald.com/2017/06/...-lobster-boat/
http://www.lobsterboatproject.com/

In Maine there is a trend for boats lobster boats and boats built using lobster boat hulls towards "no wood" boats using composite sheets and fiberglass extrusions in place of glassed in wood.

[rbgarr]

My understanding is that a problem with the trimaran design as far as lobstermen are concerned is the issue of traps getting hung up under the outer chine when hauled. I imagine Michael will have a handle on what the potential clients look for in features and shapes while pursuing greater efficiency and capabilities.

Douglas Read of Maine Maritime Academy has been working on a redesign of the Maine lobster boat using a trimaran hull to improve efficiency. One conclusion he reached early on was the boat would need to look like a traditional lobster boat above the waterline if it was to be accepted by the lobstermen. Read has projected a 30% improvement in efficiency but lower top speed capabilities. Progress has been somewhat sporadic. A 21' demonstration hull was built several years ago.
https://coastalfisheries.org/collabo...-lobster-boat/
https://www.pressherald.com/2017/06/...-lobster-boat/
http://www.lobsterboatproject.com/.

[Peerie Maa]

My understanding is that a problem with the trimaran design as far as lobstermen are concerned is the issue of traps getting hung up under the outer chine when hauled. I imagine Michael will have a handle on what the potential clients look for in features and shapes while pursuing greater efficiency and capabilities.

The draw back with a trimaran, as with all small water plane area craft is that they cannot accommodate big changes in dead weight. They are really only good for light cargoes, so the weight of the vivier tanks is a problem.
The other end of the scale is the Alaskan King crab boats, which are basically small tankers with the deck house and engine room up front.

[Breakaway]

This will be very interesting to follow,Michael. Thanks for allowing us to, " gather round the stove."

Kevin

[Larks]

I’m in!! Looking forward to seeing how you work through it and hat you come up with Mike.......(and hoping the armchair designers don’t derail your thread trying to tell you how to do your job ...)

[bluedog225]

Sounds like you have a great project. Thanks for sharing.

[John Meachen]

I look forward to seeing the proposed boat evolve.I think I have a grasp of the proposed cooling installation and it reminds me of this:

The Brabham BT46 is a Formula One racing car designed by Gordon Murray for the Brabham team, owned by Bernie Ecclestone, for the 1978 Formula One season. The car featured several radical design elements, one of which was the use of flat panel heat exchangers on the bodywork of the car to replace conventional water and oil radiators.

I don't know if there is a marine grade equivalent piece of hardware and if not maybe its time there was.Switching to a good grade of structural foam will be appreciated in a few years time when everything is still sound and doesn't smell musty.... I have known relatively low grade insulation foam used strictly as formers for the stringers and the layup was sufficiently heavy that they worked well in leisure boats that weren't at sea every possible day.

[Thad]

+++

[Ian McColgin]

Cool project.

[Gib Etheridge]

Could box coolers be built into the keel where they would be out of the way and not causing drag like the recessed grid cooler must?

It must be difficult to keep the barnacles, etc., out of a box cooler.

It seems that coolant could be pumped thru a submerged box cooler (in the keel) when not underway or when traveling at slow speeds.

[Gib Etheridge]

You've really got my head going now Michael. I'm sitting here making a lunch out of peanut butter and raisins and banana and dreaming away.

Just to show how much of a luddite I am, when I visualize keel coolers I see round pipes running along the bottom of the hull and sides of the keel, tons of drag for sure. Not only that, round pipe has the least amount of surface area of any shape so is less efficient than pipe that is rectangular in cross section, so how about this?

If the sides of the keel were double walled for the full length and the hot water were to be run thru the space between the walls it should cool very well and could be structural and faired right in as well. The outer faces could be removable for cleaning from time to time.

I guess that's what John Meachen is suggesting isn't it. Well, good idea John. What do you think of it Michael?

Back to work now, looking forward to your reply.

[Gib Etheridge]

Just one more thought. My last suggestion might be difficult to do with fiberglass, it's not strong enough and it's a poor heat conductor, but the backbone could easily be made of steel, or wide, thin (high ratio of cooling surface area to volume), steel coolers could be faired into both sides of the keel pretty easily and inexpensively.

[chas]

"The boat will be laid out in the usual configuration, and the hardware and machinery will be the tried-and-true stuff, but (and this is a BIG 'but') they have given me free rein to design the boat as I see fit to create a new, better type of boat. No wood structure (all foam-core 'glass), find new ways to make the boat mechanicals more efficient, etc. The primary directive is to do the same job as others of it's type, but see if we can make it more fuel-efficient, make the quality of the landed catch better, make it easier to work on the boat, etc."

Congratulations Michael, it must be satisfying to land a project like this. I have an interest stemming back to a time early in my career when I was an apprentice shipwright/joiner at Gooldrup Hulls out here in Campbell River. They built three boats from waxed mold stage to sail away in the time i was there in 1979-80. My favorite of the three was Mystic Era, still fished by her original owners. She has just had some hull upgrades recently and you can see some of those here.

http://www.commodoresboats.com/past-...nd-paint/#next

I look forward to following your creative process as related to the east coast fishery. / Jim

[Boatsbgood]

I'm very interested in what you come up with,and the process, and so, even though I've nothing useful to contribute at this juncture, I'll be happily following this. And, as an aside, I really appreciate when you (MMD) and other pro design folks, share, so thank you for that.
Brian

[dutchpp]

Cool project MMD.
The designs over here tend to focus extremely on serious improvement of the efficiency (fuel and handling/processing of the fish).
I'am aware of the fact that you must design within the limitations indicated by your clients but it will be interesting to see what kind of innovative idea's you'll present to us.
Enjoy the project.

[Garret]

What a great project!

Forgive my iggerence, but are external coolers used just to save space inside the hull? IOW - replacing the attached to the engine heat exchanger on a small inboard.

[Breakaway]

What a great project!

Forgive my iggerence, but are external coolers used just to save space inside the hull? IOW - replacing the attached to the engine heat exchanger on a small inboard.

Yep.. plus no intake and no strainer and no hoses. Also, corrosion is minimized. One less hull penetration.

Kevin


Sent from my iPhone using Tapatalk Pro

[Garret]

Thanks Kevin!

[mmd]

Mornin’, folks. Sorry that I didn’t get back to this last evening – other tasks beckoned.

Rather than answer each posting individually, I will try to read them as a whole and answer each point within this post. Hopefully it will work.

As I mentioned in post #12, I want to look into a ‘new & improved’ cooling system. I am not looking to re-invent the wheel, just to apply better technology to it while keeping the inevitable increase in cost to a minimum. Any technology that I apply must be robust, proven, simple, easy to install & maintain, and efficient.

Grid coolers mounted to the bottom of the hull are proven technology for half a century or more. In their simplest form they just bolt on the outside of the hull, but this creates the drag that I want to eliminate. One method to combat this is to recess the grid cooler into the hull, which almost eliminates parasitic drag. The problem is that building the recess into a fiberglass hull is labour-intensive and therefore costly. There is also the problem of perceptions by boat owners that the hull strength is compromised by cutting such a big hole in it and then tabbing pieces back in to make a hole for the grid cooler. I am confident in the structural strength, but I am not the one laying down over a million dollars for a boat with a big patched hole in it.



So, there is the alternate method of installing a box-cooler. This leaves the hull untouched except for openings cut into it to allow water circulation inside the box, which is not much different in concept and size as cutting holes for pipes. The box is easily laminated into the inside of the hull in the engine room. The shape of the hull in the engine room is conducive to water circulation within the box from both convective flow and from the boat moving through the water. WEKA makes box cooler units that accommodate multiple heat sources (main & genset) in a single unit, so that answers the simplicity requirement. Maintenance is as easy as unbolting the unit and lifting it out when the boat is hauled out for annual maintenance, and the inside of the box is accessible for cleaning and anti-fouling when the cooler unit is removed. This is the leading candidate so far, but I need to contact the WEKA engineering & sales staff to determine the unit size and cost.



Chris (cstevens) mentioned possible problems with a box cooler when machinery changes in the vessel. This is a valid point, but local experience shows that once built, the boat usually stays in its original configuration for the whole of its lifespan, which is usually around twenty to twenty-five years. The technology of the mechanicals of these boats is pretty mature, so things do not change at a very fast pace. When a big new technology comes along, usually a new boat is built around it rather than refitting an old one.

Dave Cockey posted a very relevant post about developments in lobster boat hull form that has been undertaken at the Maine Maritime Academy. I am aware of Dr. Read’s work in this field and followed the development of his trimaran hull closely (I am a fan of multihulls and have designed and built several large ones for the Caribbean tourist trade). Unfortunately, the lobster boats here in ‘SW Nova’ are radically different from the Downeast types that Dr. Read is proposing to improve upon. Our boats are much bigger – not so much in length, but in beam, depth, and volume – and a cat or tri just does not have the volume required. Our boats need to be able to carry upwards of 2,000 gallons of fuel, 300 gallons of fresh water, and have live wells capable of holding up to ten tons of live lobsters. This can be stated as a requirement of 1200 cubic feet of built-in circulated-seawater tanks, 325 cubic feet of drop-in steel fuel tanks, fifty cubic feet of drop-in stainless steel water tank, about 1200 cubic feet for machinery space, as well as crew accommodations and lazarette/steering space belowdecks in the hull. On deck there must be enough clear deck area to carry upwards of 350 wire lobster traps with ropes & anchors, a total deck load of about twenty-four tons. This equates to around 600 – 650 square feet on deck aft of the wheelhouse. Dr. Read’s trimaran, as nice as it is, just is not the proper vehicle for the task.



Gib asked whether the box cooler could be built into the keel. Sadly, no. The keel volume is pretty much taken up with shaft, bearings, bilge piping, live-well piping, hydraulic pipes, electrical conduit, and sometimes a stern thruster (not gonna be one on this boat, though). He also asked about barnacles & other fouling inside the box cooler; WEKA claims that the 90/10 copper-nickel tubing composition is naturally anti-fouling, and the inside of the cooling box will be painted with compatible anti-fouling paint. Annual inspection and cleaning will be done in the off-season.

Garret asks ”… are external coolers used just to save space inside the hull?” No, that is just a happy side effect. The engine spaces are crowded, but not extreme. There is lots of space available with some judicious re-arrangement of the mechanicals & piping. This is also something that I have been advocating for some years – a more methodical and ergonomic arrangement of mechanicals in the engine space. But to the question posed – cooling systems are closed-loop to prevent corrosion within the engines, and outside of the hull envelope for two reasons – that is where the cold water is in abundance, and it is stone-cold simple.

So, that is where the cooling system is at in this very preliminary first trip ‘round the design spiral. A box-cooler if the store-bought bits don’t break the budget.

[Peerie Maa]

So, there is the alternate method of installing a box-cooler. This leaves the hull untouched except for openings cut into it to allow water circulation inside the box, which is not much different in concept and size as cutting holes for pipes. The box is easily laminated into the inside of the hull in the engine room. The shape of the hull in the engine room is conducive to water circulation within the box from both convective flow and from the boat moving through the water. WEKA makes box cooler units that accommodate multiple heat sources (main & genset) in a single unit, so that answers the simplicity requirement. Maintenance is as easy as unbolting the unit and lifting it out when the boat is hauled out for annual maintenance, and the inside of the box is accessible for cleaning and anti-fouling when the cooler unit is removed. This is the leading candidate so far, but I need to contact the WEKA engineering & sales staff to determine the unit size and cost.

Mike, do you recall the conversation on a thread about cars on using NACA ducts and suction generating outlets to circulate water through the condensers of steam turbine supertankers? There was a paper in an RINA Journal on the topic.