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Thread: I have just been handed a boat design challenge

  1. #36
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    Default Re: I have just been handed a boat design challenge

    Nick - I vaguely recall the topic, but not the details. I am not a member of RINA, so don't think I have access to their papers. I wonder if they offer 'courtesy access' for SNAME members. Do you have a title for the paper? NACA ducts & outlets shouldn't be too hard to mold into the hull. Whether the gains in flow at ten knots or less justifies the work is a different question.

    Hugh - The hull will be laid up in an existing mold. While molding the box into the hull in the hull mold is certainly do-able from a technical standpoint, getting the hull molder to agree to do it might be another task. Also, the hull will probably be laid up in the mold starting early October, and I can't see me having time between now & then to nail this down by that date. It will be just as easy to build the box into the hull after the fact.

    David G. - There is no calculated and specified budget per se, but a number was tossed about in the meeting between the client, the builder, and myself for the total cost of the boat, which is generous. The builder & I have privately discussed what my slice of the budget would be.
    Last edited by mmd; 09-01-2020 at 10:30 AM.
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  2. #37
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    Default Re: I have just been handed a boat design challenge

    Another topic that was discussed at length in the meeting last Friday was circulating seawater in the six 5750-litre (1500 US gal.) live wells that the caught lobsters are stored in while at sea. Raw seawater must be pumped into each tank at a rate of about 3400 lph (900 gph). We will introduce a novel idea in this local fishery by introducing air into the tanks as well, via a small task-specific compressor that delivers about one-quarter m^3 (10 f^3) per hour at about 0.5 bar (7 psi). The question is how to power the seawater pumps. The system must have redundancy as you don't want to lose water circulation with $150,000 of lobsters in the tank and thirty hours from off-load if you need to be towed in. Pumps are expensive and back-up pumps require significant extra piping & valves, making space and cost the constricting forces. Current thinking is to install pumps with hydraulic motors. This way the primary hydraulic system, which is driven off the propulsion engine via a load-sensing pump, will run the seawater pumps as well as other ship-board hydraulic components, and if the main engine or primary hydraulic pump fails, hydraulic power for the live well system can be provided by either an electrically-driven back-up hydraulic pump (powered by the genset), or via a small diesel-engined hydraulic power pack. My choice would be to install the power pack, but the builder is fond of the electrically-driven hydraulic pump (he is concerned about exhaust routing, but I think - from past experience - that it is a no-brainer). Air is introduced into the seawater stream at the individual tank, so is essentially a separate system. This is a schematic of live wells piping without back-up or air introduction:

    MMD201705-050311 Live Welll Piping Schematic Rev.1.jpg
    Hope for the best, but plan for the worst.

  3. #38
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    Default Re: I have just been handed a boat design challenge

    Quote Originally Posted by mmd View Post
    Nick - I vaguely recall the topic, but not the details. I am not a member of RINA, so don't think I have access to their papers. I wonder if they offer 'courtesy access' for SNAME members. Do you have a title for the paper? NACA ducts & outlets shouldn't be too hard to mold into the hull. Whether the gains in flow at ten knots or less justifies the work is a different question.
    I have just tried to search their publications page, but the website is reporting problems.
    As you will realize, this is from waaay back, when steam turbines were powering new builds.
    My recollection is that the system was proposed to save the power required to run cooling water pumps. The intake was based on a NACA duct, but simplified to make it easy to fabricate from hull plating. The discharge was a stub of pipe with the back half cut off extending out into the flow. A clamshell facing aft would be better/less resitfull for your application.
    If it can be done it will do away with that grill intake that forms the bottom of the sea chest.
    It really is quite difficult to build an ugly wooden boat.

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  4. #39
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    Default Re: I have just been handed a boat design challenge

    Michael,
    There's a new fishing boat in Bayfield Marina (east of Antigonish) called Reel Knotty (or Knotty Reel, can't recall). She's a nice big boat compared to everything else in the harbour and looks like someone spent some ocin procuring her. Any chance you had anything to do with her? I ask because the hull looks very similar to the first layout you showed in post 1 of this thread. I too am interested in pretty much all your design threads so keep going.
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  5. #40
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    Default Re: I have just been handed a boat design challenge

    Quote Originally Posted by mmd View Post
    Another topic that was discussed at length in the meeting last Friday was circulating seawater in the six 5750-litre (1500 US gal.) live wells that the caught lobsters are stored in while at sea. Raw seawater must be pumped into each tank at a rate of about 3400 lph (900 gph). We will introduce a novel idea in this local fishery by introducing air into the tanks as well, via a small task-specific compressor that delivers about one-quarter m^3 (10 f^3) per hour at about 0.5 bar (7 psi). The question is how to power the seawater pumps. The system must have redundancy as you don't want to lose water circulation with $150,000 of lobsters in the tank and thirty hours from off-load if you need to be towed in. Pumps are expensive and back-up pumps require significant extra piping & valves, making space and cost the constricting forces. Current thinking is to install pumps with hydraulic motors. This way the primary hydraulic system, which is driven off the propulsion engine via a load-sensing pump, will run the seawater pumps as well as other ship-board hydraulic components, and if the main engine or primary hydraulic pump fails, hydraulic power for the live well system can be provided by either an electrically-driven back-up hydraulic pump (powered by the genset), or via a small diesel-engined hydraulic power pack. My choice would be to install the power pack, but the builder is fond of the electrically-driven hydraulic pump (he is concerned about exhaust routing, but I think - from past experience - that it is a no-brainer). Air is introduced into the seawater stream at the individual tank, so is essentially a separate system. This is a schematic of live wells piping without back-up or air introduction:

    MMD201705-050311 Live Welll Piping Schematic Rev.1.jpg
    Would eductor pumps take up less space?
    Really thinking out of the box, how about air lift pumps to both introduce water and aerate it at the same time.
    It really is quite difficult to build an ugly wooden boat.

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  6. #41
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    Default Re: I have just been handed a boat design challenge

    Sailor - I do not know about that boat, but as there are roughly eighty to one hundreds new boats produced annually in SW Nova, I can't keep track of them all... <grin>

    Nick - the pumps are not the space-gobblers, the piping is. As for the type of pumps, two considerations must reign supreme: cost and availability of parts & service. Next on the list is the KISS principle. I am constantly bumping into this last one. An eductor pump would still require a pump up-stream, so we are back at the original question. The air-lift pump is interesting, but the disadvantage is the need to introduce a significant compressed air supply, and possible problems with head. The water supply will be entering the live wells at about a two-metre head, and I'm not sure if an air-lift pump is capable of that with a reasonable air supply. It bears investigation, though, as it would kill two birds with one stone. Thanks for the hint.
    Hope for the best, but plan for the worst.

  7. #42
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    Default Re: I have just been handed a boat design challenge

    Quote Originally Posted by mmd View Post
    Sailor - I do not know about that boat, but as there are roughly eighty to one hundreds new boats produced annually in SW Nova, I can't keep track of them all... <grin>

    Nick - the pumps are not the space-gobblers, the piping is. As for the type of pumps, two considerations must reign supreme: cost and availability of parts & service. Next on the list is the KISS principle. I am constantly bumping into this last one. An eductor pump would still require a pump up-stream, so we are back at the original question. The air-lift pump is interesting, but the disadvantage is the need to introduce a significant compressed air supply, and possible problems with head. The water supply will be entering the live wells at about a two-metre head, and I'm not sure if an air-lift pump is capable of that with a reasonable air supply. It bears investigation, though, as it would kill two birds with one stone. Thanks for the hint.
    No wukkas. As I said, just thinking out of the box, running it up the flagpole and seeing who salutes.

    I was well impressed when the yards fire brigade dewatered a flooded boat using an eductor powered by a small portable pump on a pallet, the rig connected together with fire-hoses, which is the way that Damage Control is rigged on warships.
    It really is quite difficult to build an ugly wooden boat.

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  8. #43
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    Default Re: I have just been handed a boat design challenge

    I became well-educated on eductors while I was managing the build of two fireboats (Boston MA and Portland ME). My understanding is that they work well when pumping out of a compartment, as you describe, but not so well when trying to pump into a compartment against an existing head of water.
    Hope for the best, but plan for the worst.

  9. #44
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    Default Re: I have just been handed a boat design challenge

    Quote Originally Posted by mmd View Post
    I became well-educated on eductors while I was managing the build of two fireboats (Boston MA and Portland ME). My understanding is that they work well when pumping out of a compartment, as you describe, but not so well when trying to pump into a compartment against an existing head of water.
    Good point. I suppose that is why I have only ever heard of them as salvage equipment.
    It really is quite difficult to build an ugly wooden boat.

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  10. #45
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    Default Re: I have just been handed a boat design challenge

    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.

    Quote Originally Posted by David Cockey View Post
    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/.
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  11. #46
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    Default Re: I have just been handed a boat design challenge

    I have long hoped to see a NACA duct on a boat.

  12. #47
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    Default Re: I have just been handed a boat design challenge

    Quote Originally Posted by rbgarr View Post
    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.
    Last edited by Peerie Maa; 09-01-2020 at 06:04 PM.
    It really is quite difficult to build an ugly wooden boat.

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  13. #48
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    Default Re: I have just been handed a boat design challenge

    Very interesting thread!

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    Default Re: I have just been handed a boat design challenge

    could the base oil be cooled through an air cooled heat exchanger? no through hulls, a lot less plumbing. common on some deutz engines. may not be suitable for a larger engine.

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    Default Re: I have just been handed a boat design challenge

    Interesting thread thanks Michael, I'll be following it closely.
    Money may not buy happiness, but it can buy a boat that will pull right up next to it!

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  17. #52
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    Default Re: I have just been handed a boat design challenge

    rbgarr - Yes, lobster fishermen do not like sharp edges on the sides of their boats because traps get hung up on them. Around here, they don't even like hard chines on their boats for that reason.

    Nick - "...Alaskan King crab boats, which are basically small tankers with the deck house and engine room up front." This pretty much described the newer lobster boats around here, too.

    colin11235 - I have never heard of this type of cooling system on marine diesel engines of the size we are talking of for lobster boats (450 hp and up). Many years ago I was involved in the construction of an oceanographic research ship that was required to be able to maintain genset power while grounded out at low tide. The gensets were powered by 400-hp diesels, and the cooling was accomplished by routing the engine coolant through fan-forced radiators mounted at the base of the funnels, and they were HUGE! As these boats operate in water that is rarely above 70 deg F (and in-season, more likely to be 35 - 40 deg. F), the greatest efficiency in cooling is to use the abundant seawater as the heat sink. Gotta keep the bottom line in focus, so the simplest, most efficient method is best.
    Hope for the best, but plan for the worst.

  18. #53
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    Default Re: I have just been handed a boat design challenge

    Quote Originally Posted by mmd View Post
    Nick - "...Alaskan King crab boats, which are basically small tankers with the deck house and engine room up front." This pretty much described the newer lobster boats around here, too.
    I was thinking more about hull form, a small oil tanker form rather than the semi-displacement form of the boats you work on.


    One filmed on The Deadliest Catch series was single screw and even more like a coaster hull form than that model. Enough to make an East Coast NA Jealous?
    It really is quite difficult to build an ugly wooden boat.

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  19. #54
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    Default Re: I have just been handed a boat design challenge

    Quote Originally Posted by mmd View Post
    Nick - "...Alaskan King crab boats, which are basically small tankers with the deck house and engine room up front." This pretty much described the newer lobster boats around here, too.
    I was thinking more about hull form, a small oil tanker form rather than the semi-displacement form of the boats you work on.


    One filmed on The Deadliest Catch series was single screw and even more like a coaster hull form than that model. Enough to make an East Coast NA jealous?
    It really is quite difficult to build an ugly wooden boat.

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  20. #55
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    Default Re: I have just been handed a boat design challenge

    Although the lobster boats hereabouts evolved from a semi-displacement hull form (Cape Island hull, a lovely boat type IMHO), the newer, fat, boats couldn't semi-plane no matter how much horsepower you stuff in them. Trust me, people have tried... (But I understand your statement, both in posts #53 & 54, as well as in #47.)

    To paraphrase a lyric from a popular Canadian rock band, "She ain't semi-displacement; she just looks that way."
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    Default Re: I have just been handed a boat design challenge

    Do you get a good 3D model of the hull to work from ?

    Cheers,
    Mark

  22. #57
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    Default Re: I have just been handed a boat design challenge

    Quote Originally Posted by Mark0 View Post
    Do you get a good 3D model of the hull to work from ?

    Cheers,
    Mark
    Not yet. I will need one to do the requisite stability booklet, so I will eventually create a 3D model. The difficulty lies in the fact that the mold is not indicative of the final hull, so I cannot measure the mold and produce the 3D model. The hull will be widened and lengthened, and possibly (probably) the sheer will be raised, so I cannot determine the exact hull shape until it is built. So, the design process is a bit back-asswards from the 'normal' flow of such things. Initially I will produce a general arrangement drawing based on a set of lines that I will create. I have lines from a boat produced from the hull mold that I will modify to reflect the approximate shape of the proposed boat. From the GA and the rough-draft lines I will be able to determine approximate displacement, centres, and data for powering and prop sizing and other such stuff. Then i will calculate scantlings for bulkheads, frames, deck structures, etc., probably using DNV Rules instead of ABS (ABS Rules for 'glass tend to produce an overly-heavy boat). By then the hull will be molded and I will go to the shop and measure the hull for exact shape and create the final 3D model.
    Hope for the best, but plan for the worst.

  23. #58
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    Default Re: I have just been handed a boat design challenge

    Quote Originally Posted by mmd View Post
    Not yet. I will need one to do the requisite stability booklet, so I will eventually create a 3D model. The difficulty lies in the fact that the mold is not indicative of the final hull, so I cannot measure the mold and produce the 3D model. The hull will be widened and lengthened, and possibly (probably) the sheer will be raised, so I cannot determine the exact hull shape until it is built. So, the design process is a bit back-asswards from the 'normal' flow of such things. Initially I will produce a general arrangement drawing based on a set of lines that I will create. I have lines from a boat produced from the hull mold that I will modify to reflect the approximate shape of the proposed boat. From the GA and the rough-draft lines I will be able to determine approximate displacement, centres, and data for powering and prop sizing and other such stuff. Then i will calculate scantlings for bulkheads, frames, deck structures, etc., probably using DNV Rules instead of ABS (ABS Rules for 'glass tend to produce an overly-heavy boat). By then the hull will be molded and I will go to the shop and measure the hull for exact shape and create the final 3D model.
    As you have the lines from the mould, is there no chance of you doing the stretching/jumboising on the screen, then telling the builders what to do when you know that she is as safe as you can make her?
    It really is quite difficult to build an ugly wooden boat.

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  24. #59
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    Default Re: I have just been handed a boat design challenge

    I could do that, Nick, but it would run head-on against the "that's the way we always done it" attitude here. I will save that change of design/build method for later on down the line, and will, for now, revel in the fact that I have a chance to change features that affect structure and efficiency with this one. I am confident in the stability of these boats, and will have a kick at structural soundness prior to the build, so I am happy for now. Baby steps; baby steps...
    Hope for the best, but plan for the worst.

  25. #60
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    Default Re: I have just been handed a boat design challenge

    I can visualize how a boat might be lengthened, I can't understand how it can be widened. Do they separate the hull longitudinally? Then fit a piece of fiberglass parallel between the two halves, doesn't that mean they end up with an over-wide stem?

    Finally, if they do something like that. Would that not be a good time to fit a recessed keel cooler?

  26. #61
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    Default Re: I have just been handed a boat design challenge

    "Raw seawater must be pumped into each tank at a rate of about 3400 lph (900 gph)."

    Water being pumped in also has to go out. Is 900 gph enough flow to put the heat exchangers in line with the output from the live wells? They could get built into chambers with a seacock at either end to isolate them for maintenance from inside the boat and the output could be above the waterline.
    Steve

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  27. #62
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    Default Re: I have just been handed a boat design challenge

    Gareth - Widening the boat is quite a process and, like making sausages and laws, not for the weak of heart to witness. There are a couple of methods used locally:

    One method, mostly for moderate amounts of widening the hull, entails laying up the hull in the mold with about 1/3 to 1/2 of the requisite laminate stack, removing the hull from the mold while still green and flexible (about two days after laminating) and supporting it on jackstands. Two longitudinal cuts are made from transom to within about five or ten feet of the bow and the outer parts spread apart to the desired beam. Flat panels that have been previously laid up (usually on sheet plastic laid on the shop floor) are served up to the vee-shaped openings in the hull, templated and cut to fit, edges ground to a bevel, and tabbed into place. Then the final layers of laminates are laid in the interior of the hull to achieve the requisite hull thickness. The seam on the outside is ground a bit and a layer or two of 'glass is laid along the seam to seal it. This method, when used to extremes, produces a boat that is rather wedge-shaped, with the transom being the widest part of the hull. Fishermen like them, though, because it reduces the likelihood of a string of traps fouling on the gunwales when 'shooting away'.

    The second method is more fussy to do, but IMHO produces a better hull. The centre strip of the hull, about four feet wide and encompassing stem, keel, skeg, and a strip of the hull from sternpost to transom is laid up, again with about 1/3 to 1/2 of the requisite laminate stack. The mold is split open (these are all two-piece molds joined at the centreline) and spread out about a foot on each side and moved aft so that the edges of the strip of hull at the bow quarters touches the mold, and another two feet of hull is laid up. Rinse and repeat. When the desired extra beam is achieved, then the rest of the hull is laid up to produce a full hull at the desired beam. Then the final layers of laminates are laid in the interior of the hull to achieve the requisite hull thickness. This method produces a hull more closely conforming to the original hull shape, except wider. I think that this method produces a stronger hull, too, but the point is rather academic, as the hulls are so overbuilt that they are pretty much bullet-proof.

    Fitting of odd things in the hull at time of molding makes sense, but most of the shops that make hulls for others don't want to mess with the routine they have already established to make a hull. Remember my favourite line to hate: "That's the way we always done it." Laminators aren't the most adaptable of people; they are mostly 'head-down, work hard, don't think outside the box 'cause that's where mistakes lie' kind of folks.

    Steve - we have given some thought to using a variation of that idea to cool the hydraulic fluid in the rope locker (which is flooded to keep the lines from tangling), but not for main & genset cooling. There will always be water in the rope locker when the hydraulics are running because if the hydraulics are on, they be fishin'. However, when in-transit to the fishing grounds, or doing another form of fishing - such as for scallops - the live wells are not in use and therefore have no seawater supply.
    Hope for the best, but plan for the worst.

  28. #63
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    Default Re: I have just been handed a boat design challenge

    Depending on the depth of the keel, it might be possible to bond/laminate a quad section of tube, if not some more angular section over the corner of keel and bottom (hog or garboard).This tube-like cavity is flooded and houses a copper coolant tube or two passing along the full length of the hull on both sides, perhaps even looping at the bow end to be continuous.Faired into bottom and keel, this cowl like add-on effects a fairly small addition of wetted area, if capped at the fore end, and should require only minor ducting to open for entry of heat exchange cooling water.

  29. #64
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    Default Re: I have just been handed a boat design challenge

    Lugalong, before I reply directly to your post above, allow me to describe my thought processes in evaluating a new idea - mine included (especially mine): Whenever I am presented with the 'next great idea', I attack it from every angle I can think of to try to find its weak point(s). Often, I will invite others whom have experience in the subject to attack it, too. IF it can survive this withering attack, it is probably a good idea; if a crack is found, then the idea needs to be either re-thunk, or trash-canned. So please do not take any criticisms I may put forth as anything personal - it is just the way I go about such things. Now to your proposal:

    Your proposal is intriguing, but I see a few issues that might arise in my application. Firstly, how is this fundamentally different from the method of running a loop of pipe longitudinally along the hull, tucked up under the turn of the skeg/hull intersection as is normally done around here? It seems that your proposal is the same concept, but in a different location. Second, the local method places the pipes on the opposite side of the skeg from the side of the boat that pots are hauled from, thereby removing them from possible harm from the hydraulically-propelled sixty-kilo pot; if I understand your description correctly, your proposal would put the cooling pipe in harm's way at the edge of the keel/skeg (you would not believe the scarring on the stbd keel side from ropes being hauled across it). Third, as we operate in a region with tides in the range of six to ten metres, the boats quite often ground out at low tide att heir home wharf - how would your method stand up to being repeatedly buried in the mud and then lifted out by irresistible forces, or being crushed by the boat drying out on a gravel bottom against a wharf and leaning into the wharf by ten degrees or so? Finally, and again if I understand you correctly, I think that the reduction in drag would be minimal, as the primary source of drag would be skin friction along the length of the semi-open piping, not appendage drag from the frontal area of the pipe/tray combination.
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    Default Re: I have just been handed a boat design challenge

    First, I like to thank you for this interesting thread.
    Then I have a (and I admit maybe naive) question: how much money is saved overall (considering te total boat cost) by using an existing female mold and modifying the product instead of laying up over a temporary mold? After all surface finishes are already compromised by modifying the hull and if "workboat finish" is acceptable, modern CAM aided methods can produce a quick female (or male) mold into wich one can infuse a hull. This way the designer can produce the best product from dy one, instead of working around limitations. It can not be cheap paying the designer to come out, measure the produced hull and alter all drawings to fit the product, or transporting the hull from one boatyard to another.
    I also have to ask if a boat of this size and expected lifespan would not be cheaper to make in unpainted aluminium or steel.

    As for pump redundancy is there a reason the generator engine can not also be fitted with a hydraulic pump (with clutch) besides the electric head? Than fit a second set of electric driven pumps as backup to the hydraulic ones, and you have two engines backing the hydraulic system and all electric pumps backing the hydraulic ones. For full redundancy you would have to fit a backup generator, preferably aircooled, that also has the clutch and mounting points to take one of the existing hydraulic pumps.

    I hear you when you talk about changing the conservative views of the people, but at the end of the day it's an economic question. How much money can we save by going infusion (less wages for laminators), temporary CAM molds (less manual work overall), different materials, etc. and produce the best boat for the job. After all, in the right location (materials, labours) even modern wood construction can make sense for the expected lifespan.

  31. #66
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    Default Re: I have just been handed a boat design challenge

    I'm late to the thread here, but I do find these issues fascinating. I'd like to go back to the original post to ask about the proportions of these boats. Are there regulations that set a limit on length or tonnage here? I don't see another reason for such a wide boat when efficiency is important.

    -Dave

  32. #67
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    Default Re: I have just been handed a boat design challenge

    I've been wondering if any aspect of the fishery that these boats are involved in would require freezing capability. / Jim

  33. #68
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    Default Re: I have just been handed a boat design challenge

    Rumars, excellent questions, all.

    "...how much money is saved overall... instead of laying up over a temporary mold?" Bluntly, about fifty thousand dollars - enough to give builders and owners the willies if you suggest it. It is much, much faster to slice 'n' dice a hull than to build a temporary mold. As for compromised surface finishes, most of the builders here are so familiar with the process that I would challenge you to find the 'seams' on the hull surface where the hull was widened. The nearest CAM facility capable of making molds of the size required - even in pieces - is hundreds of miles away in another country (USA), which at the best of times would create huge transportation expenses and duties/Jones Act complications. With Mr. Trumps current antipathy towards Canadian industries and nascent interest in the Maine lobster industry, any interference in mold delivery could spell financial disaster for the builder and owner. Better to let sleeping dogs lie.

    "It can not be cheap paying the designer to come out, measure the produced hull and alter all drawings to fit the product, or transporting the hull from one boatyard to another." It costs about $5,000 to measure the hull and produce a lines plan. Delivery by road costs about $1,000 - $1,500 (pretty much all the local boatshops are within 100 kilometers of each other, and there are several transport companies with specialist trailers specifically for moving boats of this size). Towing a boat from shop to shop is usually done by another fishing boat - usually a friend or relative of the client - and often costs only the price of fuel for the boat and booze and a BBQ for the towing crew. When the cost of the completed boat is often north of a million dollars, a few thousand to move a hull from shop to shop is just a minor expense.

    "I also have to ask if a boat of this size and expected lifespan would not be cheaper to make in unpainted aluminium or steel." FRP is less expensive to build than either aluminum or steel by a very large amount - probably in the order of a couple hundred thousand dollars. FRP requires very little specialized equipment in the shop, and a laminator - even a good, experienced one - gets paid about half of what a journeyman welder would command. Material costs are lower, per pound, too. Don't get me wrong - I would much prefer to do a custom-designed aluminum fishing boat than 'glass, but the market will not support it.

    "...is there a reason the generator engine can not also be fitted with a hydraulic pump ...? Yes; genset manufacturers will usually void the warranty on the unit if it serves double-duty as a source of non-electric power.

    "I hear you when you talk about changing the conservative views of the people, but at the end of the day it's an economic question" Yes, it is an economic question, and given the robustness of the local FRP boatshops experience vs. the dearth of metal shipbuilding skills in the region (there is one, and they are expensive - I used to work for them), the "normal" way of building FRP boats is by far the least expensive method. I am quite pleased and mldly surprised that our client is prepared to pay a premium price for this boat so that we can address some of the issues that I see need improving. If we pull this one off and actually do build a better boat, we hope that word will spread and the builder (and me by association) will garner more work based on it and in future be able to pull the industry into the 21st century and implement other more technical processes. As for wood construction, as much as I like it and have worked with it in yacht construction, the last major wood commercial boatbuilder in the province switched over to building 'glass boats about ten years ago, after a very long and painful decline of their fortunes. Even the much-vaunted composite-wood yacht builder Covey Island Boatworks is now building 'glass fishing boats. Times have changed and the industry has moved on.
    Hope for the best, but plan for the worst.

  34. #69
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    Default Re: I have just been handed a boat design challenge

    Dave - there is a limit on length; 15 meters LOA (49 ft 2 in). There is a 'break point' at 15 GRT where more stringent inspection and safety requirements kick in, but these do not affect the proportions of the boat. The 'why' of the extreme beam is a bit long and convoluted, but essentially the fisherman want to carry all of their lobster pots at once, which requires significant deckspace and carrying capacity. In one of my earlier posts (post #30) I listed the capacities required.

    chas - nope; no freezers. The boats rarely stay out for more than four or five days, and the catches are kept alive in seawater-filled live wells.
    Hope for the best, but plan for the worst.

  35. #70
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    Default Re: I have just been handed a boat design challenge

    Quote Originally Posted by mmd View Post
    Dave - there is a limit on length; 15 meters LOA (49 ft 2 in). There is a 'break point' at 15 GRT where more stringent inspection and safety requirements kick in, but these do not affect the proportions of the boat. The 'why' of the extreme beam is a bit long and convoluted, but essentially the fisherman want to carry all of their lobster pots at once, which requires significant deckspace and carrying capacity. In one of my earlier posts (post #30) I listed the capacities required.

    chas - nope; no freezers. The boats rarely stay out for more than four or five days, and the catches are kept alive in seawater-filled live wells.
    Yea, we should have thought about this while building our boat. We are 15.62 meters, would have been no problem building <15meters. Granted we aren't commercial, it would have saved a bit of money during the registration process.

    I'm surprised a steel hull would be so much more costly !

    Cheers,
    Mark

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