True displacement models

I took a flight out to Salt Lake City to do some skiing about 6 weeks ago. I pinched a nerve in my neck trying to snooze in that ridiculously cramped seat, didn't do any skiing, caught a heck of a cold on the flight back and haven't been back on my boat since. Coughing and hacking, I pulled a muscle in my lower back. Between Dr.s appointments, icing, heat and acupuncture, maybe I'll finally get back to the boat this week, and actually finish the thread on swapping the Genset, but probably not.

No argument from me

FF said:

>The flat aft sections have a benefit at anchor as the boat has zero roll, rock solid<

All boats that are basically flat on the bottom will stay parallel to the water surface .

Dock side this is great as there is little movement when folks climb aboard.

The problems only come when the water surface is NOT flat.

Then the bottom will also stay parallel to the water surface and a 6-8 ft or larger waves abeam can create a very rough ride.

Not a hassle for most inshore operation, where even with high winds there is little fetch to create larger waves.

While the round bottom of a full disp boat will allow some motion at all times the difference is the entire hull is lifted by a wave , rather than the chine corner beginning to rapidly roll the boat.

There is also a huge difference in the way the roll stops as the wave passes under.

The slow soft check of the disp boat is far kinder than the hard check, almost snap of a boat with corners well immersed.

Watch a log go by in rougher water , it mostly just goes up & down , watch a floating box go by , it follows the rough water surface .

Boats are designed to operate in specific conditions , operating one in a condition it was not designed for can be uncomfortable.

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With light boats this is absolutely true. At 66,000 lb the Hatteras doesn't exactly bob like a cork. The flat aft sections combined with the very round mid section actually track very well. This boat has stabilizers which I believe play a major roll in maintaining course in following seas, since I haven't experienced this boat without them I can't say how much of an improvement they make. But it makes sense that they do because they control the heeling as the the stern rises and what ever broaching effect there is created by the heeling of the boat. I have been in some pretty large seas with this boat and it tracts like it was on rails. My last boat was a 4788 Bayliner. The Bayliner is very light and has a very flat bottom. Following seas of moderate size was not a happy place at displacement speeds. Fortunately it had great performance and could easily stay at wave speed and ride the back side of moderate seas. It also had the ability to plane and cruise at 18knts, actually go somewhere on a weekend. At anchor the 4788 was rock solid. No boat is perfect for every condition and use.

Scary points out one of the critical issues in picking a hull type engine and all related gear. Its best to match what you get to how and where you are going to use it. The hard part is doing an honest job in that department. I have heard marine architects and builders complain about this dichotomy of what the client wants and what they most likely need.Too often people get hooked up to a boat and gear that is meant for something other than how it is used. An example, what's the point of having a great slow sea boat if most of your time is spent in sheltered waters and at anchor and the sea boat includes a lot of compromises that don't go well with that use pattern.

Damn, what are the injury stats for trawlering? From this thread, it is way more dangerous than I was led to believe! Hope all recover quickly.

Some good points raised.
There is a wide variety of uses of boats, sea/lake/river conditions, and personal preferences. For all these reasons there is not one type of hull shape that is best for all. My perfect hull may be a disaster for someone else, and vice versa.

THD said:

Damn, what are the injury stats for trawlering? From this thread, it is way more dangerous than I was led to believe! Hope all recover quickly.

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Yes but don't forget we have a sitting on airplane injury too. I had to do that all day Saturday, East Coast to West Coast. It's far worse than a boat in choppy water.

Everyone's tolerance is different. There are multiple levels. We go from those who only want lake smooth to mildly bumpy to uncomfortable to unsafe. Most of the boats are capable of handling far more than we actually want to be on them handling. And each boat made to perform better in different conditions.

My injury was non-boating related. As much as we are stumblebums, our boating injuries have been first-aid kit minor; though a cruiser friend who is a nurse did splint my little finger on one occasion. Remember, the definition of cruising is fixing your boat (and body) in exotic locations.

Spottsville said:

All Great Harbour Trawlers are true Full Displacement hulls. All are twin engine with keel protected props and a shallow draft making them great for the Great Loop, inland rivers, ICW shallow areas and ocean capable! Built with quality materials and solid construction.

Great Harbour Trawlers - Great Harbour Trawlers: America's go-anyhere liveaboards

Norm Miller
Quiet Company
Great Harbour GH47

Sent from my iPad using Trawler Forum

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Greetings Norm,
So how is Quiet Company holding up?
Have a great 2017
Jim

Barpilot said:

I'm not interested in a discussion of full vs. semi-displacement. I was looking for any information, based on fact/experience, as to what model/manufacturer are true full displacement. Using the search engine is like searching for a single screw on Yachtworld. You get a list and when you see the actual pictures you quickly find that half of them are twin screw. I'm looking for a true full displacement trawler, 1980 or better, under $150K. Who did or currently makes one?

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Barpilot, if you're on the east coast check out my friends Willard 40 on yachtworld...For a few dollars over $100k you can own a genuine full displacement trawler with long range capabilities. If you're on the west coast, check out my W40 which will soon be up on yachtworld.

Fish Catcher Jim said:

Greetings Norm,
So how is Quiet Company holding up?
Have a great 2017
Jim

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QC is holding up very well! We are doing an HVAC update right now to be ready for another year of cruising. Love the boat and proud to own it!
Norm

Spottsville said:

QC is holding up very well! We are doing an HVAC update right now to be ready for another year of cruising. Love the boat and proud to own it!
Norm

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Hi Norm,
Ya know your you tube chanel is looking a little lonely these days. Hint Hint.
Sure did like the front row seat you had at the air show.

Have you done any more changes lately? The last ones I remember were lights in the engine room.
Glad to hear All is Well
Have a wonderful cruising season.
Jim

Greetings
Have a question on hull designs on full displacement hulls.

Question:
Comparison of Afts
Great Harbour N series
Compared to something like
Cheoy lee or Krogen Aft.

How well does the Aft of the GH N series ride and handle bigger waves and following seas?

The GH N37 is starting to look like a good starter loop trawler but have not ever seen one in bigger seas or following waves running faster then the boat.

Thank you for your replies.
Jim

That's a question for Joe Pica. He has over 40k miles riding his N37 and is very well versed on the ins and outs of the N37s hull design and following seas. My GH47 does very well with the rise in the hull in the stern. The waves run right under it with a minimum of push. What do you mean by a Starter loop trawler?

Fish Catcher Jim said:

Greetings
Have a question on hull designs on full displacement hulls.

Question:
Comparison of Afts
Great Harbour N series
Compared to something like
Cheoy lee or Krogen Aft.

How well does the Aft of the GH N series ride and handle bigger waves and following seas?

The GH N37 is starting to look like a good starter loop trawler but have not ever seen one in bigger seas or following waves running faster then the boat.

Thank you for your replies.
Jim

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I would think any FD power or sail hull in an inlet or NW rapids with waves breaking faster than the boats top speed is in a potential bad place. Actually safer running under those conditions is better done in fast boats that can match or ride the waves and water flowing onto stern. Running bow first into fast moving water is also safer in faster boats that can get more than a few knots on the current and FD craft are at a big disadvantage when the top speed may be 5-8K. I have boated many years on the New Jersey coast and now in the PNW where the above described conditions are common. I give a big thumbs up to a fast SD or planning hull which I typically use(SD) at or just below displacement speed until I find myself in fast water or bigger waves or running for cover then I burn the fuel. I also would like to reinforce what has been said about a SD hull vs. FD and fuel burn both can be highly efficient actually the boats weight beam length and prop are more important than the designation SD or FD when it comes to fuel burn. I also believe engine size and # of engines is erroneously attributed too much attention regarding fuel burn particularly on a modern engine that will carefully meter fuel to load. At idle the binger engine burns slightly more but you should idle as little as possible otherwise the amount of fuel used depends on the load or HP needed to turn the prop. The friction and heat loss of the larger engine will theoretically cost more fuel but not very much and many other factors will completely hide that difference. If two identical boats in all ways except engine size are compared the major fuel burn difference would be on the speed traveled and the load demanded of the engine. Ride characteristics are more likely related to hull type. There are good reasons why most recreational boats which are not used to cross oceans are not FD for the most part the draw backs out weigh the benefits. Pun somewhat intended.

There are cresting waves (deep water) and breaking waves (shallow enough for bottom to take effect)....big difference in needing speed unless in a true survival situation.


Most boats will survive cresting waves with or without a drogue until they become something most of us will never see.


Uncomfy? You bet


Poop a cockpit? often


So a quick, self draining boat is usefull...but as to the whole hull design...maybe not as much.

Spottsville said:

That's a question for Joe Pica. What do you mean by a Starter loop trawler?

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Hi Norm,
Yep I think that would be a good thing to get Joe's thoughts on this.

Lol - Ok what I mean by a starter loop trawler.
Things changed and we had to put off doing anything but the trawler desire has not left so once again we are looking into purchasing a trawler.

The GH N37 with its big engine room and boulsons locker draws us more then the GH at this time. Not to mention these boats just stand out to us.

The 37 feet will be easier to find anchorage then most and the GH N series is closer to a much larger layout.

So getting our feet wet so to speak in living aboard full time , the Loop seems like the best choice to start with and will give us better then a year building our experience and then We can decide if we go forward or back to the hard.

Then we will know whether we want to stay intercoastal or more open and blue water passages.

If we desire to go more open crossings, well we would truly move up to the original desires in the 58 to 75 foot range. Maybe even include another couple.

Either way sir, the N37 seems to be the best starting point and easiest. After a year or so, well we may decide to stay in it or move up. That's what I mean by starter loop trawler.

Have a wonderful cruising season
Jim

eyschulman said:

I would think any FD power or sail hull in an inlet or NW rapids with waves breaking faster than the boats top speed is in a potential bad place. Actually safer running under those conditions is better done in fast boats that can match or ride the waves and water flowing onto stern. Running bow first into fast moving water is also safer in faster boats that can get more than a few knots on the current and FD craft are at a big disadvantage when the top speed may be 5-8K. I have boated many years on the New Jersey coast and now in the PNW where the above described conditions are common. I give a big thumbs up to a fast SD or planning hull which I typically use(SD) at or just below displacement speed until I find myself in fast water or bigger waves or running for cover then I burn the fuel. I also would like to reinforce what has been said about a SD hull vs. FD and fuel burn both can be highly efficient actually the boats weight beam length and prop are more important than the designation SD or FD when it comes to fuel burn. I also believe engine size and # of engines is erroneously attributed too much attention regarding fuel burn particularly on a modern engine that will carefully meter fuel to load. At idle the binger engine burns slightly more but you should idle as little as possible otherwise the amount of fuel used depends on the load or HP needed to turn the prop. The friction and heat loss of the larger engine will theoretically cost more fuel but not very much and many other factors will completely hide that difference. If two identical boats in all ways except engine size are compared the major fuel burn difference would be on the speed traveled and the load demanded of the engine. Ride characteristics are more likely related to hull type. There are good reasons why most recreational boats which are not used to cross oceans are not FD for the most part the draw backs out weigh the benefits. Pun somewhat intended.

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Hi eyschulman,
That all makes sense and that's one of the reasons we looked into a hand full of Flemings. They seem to cover these type of situations very well.

For now being loopers and some open crossings seems to be where we are headed and the lower powered FD trawlers seems to make good sense.

Thank you again
Jim

It would be difficult to find a more spacey and convenient live-aboard for doing the loop than the N-37, IMO, but they do bring a premium. How about the fly-bridge, yes or no?

healhustler said:

It would be difficult to find a more spacey and convenient live-aboard for doing the loop than the N-37, IMO, but they do bring a premium. How about the fly-bridge, yes or no?

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Hi Larry,
Fly Bridge? Truthfully it certainly is not a deal breaker either way. We can see an advantage both ways.
Guess we will see what is available when we are ready to step on out there.

Jim

That makes sense! We are more one goal at a time. For us and the boating we are going to do the Great Harbour is ideal. We have a large family and like the three cabins. I'm not a fan of sleeping on couches so we avoided that set up. Our settee in The Pilothouse makes into a queen size bed but to date we have not used it. 2 and a half heads, full sizes appliances and an insane amount of storage is tops on our list. Hell I even have a 55 in UHD LED TV on the aft wall of the Pilothouse. We burn 3.5 GPH and with a 320 gallon holding tank 480 gallons of fresh water 1300+in fuel we can stay remote for a long period of time. We cruised from 792 on the Ohio this year to Knoxville TN (the beginning of the Tennessee river) and back. Next year we plan to cruise to the 0 MM on the Ohio and maybe on down into West Virginia then back home to mm792. Then the plan is to start the loop (after we have hit all the inland rivers in the Midwest. We live in the sweet spot for cruising the inland rivers! The Ohio, Green,Cumberland and Tennessee and we will do the southern part of the Mississippi when we leave for the loop. Blue water is not currently an attraction for us with so much inland for us to see. I've done the jump from Mobile to Fort Meyers and Fort Meyers to Mobile and enjoyed it but and I'm not drawn to it. We enjoy the constantly changing scenery inland and it's less crowded and less stress.

Great Harbours are built really well! I mean solid! They are true Full Displacement Trawler Yachts and have great range and are economical to maintain and operate. I love the hard chine and the hull is designed to be stable not rolling. I bought mine through Ken Fickett at Mirage (the co-designer with Loe Codega and the boats builder). It is great to be able to pick up the phone and have a true expert on the boat willing to help you keep it in great shape. He has a real passion for his boats and will tell you what he thinks. That to me is very valuable. He has a line on some good N37s right now I beleive.

Good luck on your search!

Fish Catcher Jim said:

Hi Larry,
Fly Bridge? Truthfully it certainly is not a deal breaker either way. We can see an advantage both ways.
Guess we will see what is available when we are ready to step on out there.

Jim

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Remember a flybridge is like have an additional large room. Sometimes seperate spaces when you need some alone time worth a lot. And the wind and the sun on many days is life at its best in my book!

We did the Loop this year in a GH47 (138 miles to complete for the gold burgee). We enjoy the fuel economy, the comfortable living and the shallow draft. We are glad we did not have a flybridge - this allowed us to cruise downtown Chicago bridges and the Lake Champlain canal bridges (last year). We traveled with a GH37 this year and both boats had a great time. We love the raised pilot house.

Fish Catcher Jim said:

Hi Larry,
Fly Bridge? Truthfully it certainly is not a deal breaker either way. We can see an advantage both ways.
Guess we will see what is available when we are ready to step on out there.

Jim

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I've tossed around the idea of either version. The boat already has good vision from the pilothouse, but the fly might have a docking advantage. For bridge clearance and windage, no fly. Southern temps and Bahamas make the fly version a little nicer, especially for reading the clear waters. Roof space for solar, no fly. Entertainment aboard....fly. Maintenance and cost for duplication of at least some helm electronics, no fly.

Here's the way I see it. The conundrum comes down to the number of places each of you have to escape the company of the other (something that may become necessary when in such close quarters for extended periods). You have the engine room/workshop/man cave area and the boson's locker (big enough for a recliner, TV and beer fridge). If one considers the master stateroom and salon/pilothouse common areas, that leaves her with the spare stateroom/office as her only option for escape. The fly bridge offers her that 2nd alternative. Fly-bridge model wins.

My case is a little different. Since my second alternative space (the boson's locker) would be filled completely with my Admiral's shoes, we would each need only one individual area of escape, mine being the engine room and hers being the spare stateroom/office. Hence, the no-fly wins.

I could not agree with you more there Norm on all that space and real beds on those GH models!!
I thought you had added the tv.

Your plans sound awesome.
I really wish I could wrap my head around the engine room in the GH. Those in the N just seem right. Lol

Yes sir those inland waters and rivers are a joy and beauty to behold and the folks along the way can be a true joy to meet.
Ahhh but then there is all that Fishen to be done.
Looking forward to hearing about your adventures.
Jim

Someone (preferably a naval architect ), please correct me if I'm wrong. I've read on this thread people claiming to have full displacement boat with a hard chine and shallow draft. I'm not disputing them, just trying to gain a better understanding of vessel design so I don't keep appearing ignorant forever. My understanding was full displacement hull has a rounded belly. As for shallow draft, how do you define that? As a draft less than a specified amount, or as a draft of x feet per y feet of length? I ask this because I've always been under the assumption that full displacement hulls tended to deeper drafts (sp. draughts). I'd rather appear ignorant once but be corrected than sound a fool every time I tried to speak on the subject.

Well I'll take a shot at your question. The simple answer is Full displacement boats are not designed to plane off. Instead the water moves around the boat think tow boat on inland rivers or ocean work boat like the one in the picture. You can increase horsepower but more push wont result in the boat planning . As for shallow draft, for the Great Loop and ICW 3 foot or less would be IMO a shallow draft boat. Our GH47 is 2.5 to 3 ft depending how much water, fuel and blackwater we have on board.

healhustler said:

I've tossed around the idea of either version. The boat already has good vision from the pilothouse, but the fly might have a docking advantage. For bridge clearance and windage, no fly. ...

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No flybridge, thank you.

Spottsville said:

Remember a flybridge is like have an additional large room. Sometimes seperate spaces when you need some alone time worth a lot. And the wind and the sun on many days is life at its best in my book!

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Yes Sir that would be one of those pluses for sure

HenryD said:

We did the Loop this year in a GH47 (138 miles to complete for the gold burgee). We enjoy the fuel economy, the comfortable living and the shallow draft. We are glad we did not have a flybridge - this allowed us to cruise downtown Chicago bridges and the Lake Champlain canal bridges (last year). We traveled with a GH37 this year and both boats had a great time. We love the raised pilot house.

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That sounds so awesome!!
I agree that the Raised Pilot house are a pluss and holds a place in my heart for sure.
The GH 47 was the first Great Harbour we liked but then I saw the engine room and boulsons locker on Gale Force N47 and we were hooked.
Looking forward to reading about your traveling for sure.
Have a great Season
Jim

healhustler said:

I've tossed around the idea of either version. The boat already has good vision from the pilothouse, but the fly might have a docking advantage. For bridge clearance and windage, no fly. Southern temps and Bahamas make the fly version a little nicer, especially for reading the clear waters. Roof space for solar, no fly. Entertainment aboard....fly. Maintenance and cost for duplication of at least some helm electronics, no fly.

Here's the way I see it. The conundrum comes down to the number of places each of you have to escape the company of the other (something that may become necessary when in such close quarters for extended periods). You have the engine room/workshop/man cave area and the boson's locker (big enough for a recliner, TV and beer fridge). If one considers the master stateroom and salon/pilothouse common areas, that leaves her with the spare stateroom/office as her only option for escape. The fly bridge offers her that 2nd alternative. Fly-bridge model wins.

My case is a little different. Since my second alternative space (the boson's locker) would be filled completely with my Admiral's shoes, we would each need only one individual area of escape, mine being the engine room and hers being the spare stateroom/office. Hence, the no-fly wins.

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Thank your for the big smile and laugh here Larry.
Well mine will be a litter different then that.
Half boulsons locker knitting and sewing stuff.
The other half supplies, parts and Fishing Gear.

She gets the space where ever Except Engine Room Helm area and small space in saloon for my chair and foot stool. Lol

As goes the flybridge. .... as long as I can get a good tender for fishing up there then all will be good.
There are some very nice Lite Aluminum boats that would work well. Lighter then most ribs.

Kind of like the mast over the arch and stairs in front rather then the back deck as with the flybridge on the N but I can deal with either.

Thanks again
Jim