Messages

16

Introductions - Are you new here? Say hello! / Re: Cruising focused GA 30

« on: November 04, 2024, 03:11:25 PM »

Regrettably, I am probably a couple of years out from building. I have quite a punch list to finish on our home I built here and some work to make my shop useable for boat building. I am digesting your reply on the platform thread. Thanks for that.

Maybe a Gen II GA would convince you to put off all those other items and start working on a boat!  Here's what I'm thinking, noting that a 25-26 ft boat doesn't have as much room and has not been 'targeted' to be someone's live-aboard boat and is good as-is:

1. If building a 25 to 26 ft Great Alaskan, then build the Gen-I Standard GA

2. If building a 27 to 28 ft Great Alaskan, then build the (upcoming) Gen-II Standard GA  (optimized for a more distributed load)

3. If building a 29 to 30 (maybe 31) ft Great Alaskan for live-aboard accommodations, then build the (upcoming) Kodiak Explorer GA (Gen-II Kodiak) (optimized for a more distributed load)

4. If building a 29 to 30 (maybe 31) ft Great Alaskan for commercial fishing or for charter, e.g. 6-pack Captain's License, then build the Kodiak Commercial GA (Gen-I Kodiak)

Names are subject to change and I'm totally open to input!  There will be optimized 3D CAD models and CG spreadsheets for all of the above... And in the mean time, I've got about $3.2k to drop on software renewals (BricsCAD, Rhino 3D, and Orca 3D).  I intend to design the CG spreadsheets for general use by the public if that's even possible.  My original spreadsheets were adapted from US Navy ship design spreadsheets and need to be simplified to make them more flexible and easier to use.

Brian

17

General Discussion about the Great Alaskan / Re: extended swim platform

« on: November 04, 2024, 02:59:20 PM »

Howie ... When do you think you'll start building?

18

Introductions - Are you new here? Say hello! / Re: Cruising focused GA 30

« on: November 04, 2024, 07:34:26 AM »

Hi Brian-

I should have been more clear. Looking at 30-foot waterline boat. For sure wanting to do a "euro" transom, with a door as others have here. for me, it seems like the ease of boarding and extra length is worth the extra work.

You're on the right track in paying attention to layout and where weights go.  See my response to your other thread on the swim platform topic.  When do you plan to build?  I may have my updated CG spreadsheets and boat modeling updates done by then and it'd be easier to help you make decisions on layout.

19

General Discussion about the Great Alaskan / Re: extended swim platform

« on: November 04, 2024, 07:32:00 AM »

Well thought out!  I like that!  IMHO, there's nothing wrong with a 'wing type' (as you call it) swim step/platform on one side.  I'd go with a thru-hull transponder or put your transom type under the swim platform side ... kicker on the other.  As far as weight and balance go, keeping in mind that 2/3rds of a planing hull is forward of the CG, you should take into careful consideration all that goes f'w'd.  If you are going to highly-outfit the boat for almost live-aboard accommodations, then it may mean a disproportionate amount of weight ending up f'w'd of the CG as mentioned.  Using those 'wing type' swim platforms and the main on a bracket to move it aft, then that's an opportunity to help move the CG aft if your accommodations are moving it f'w'd.  This is true more so for the Kodiak, which was designed for 'commercial or serious recreational fishing" ... in other words, more stern weight capacity. 

A good way to estimate your CG location is to look at the 000x series of drawings that come in the plans and study the construction details very carefully ... if you build the boat exactly as shown in those drawings, it will trim 2-1/2" up at the bow.  Whenever you add something heavy f'w'd of the CG that is in excess of what you see in the 000x drawings, then figure out a way to counteract it with weight of some sort behind the CG ... compare moment-arms.  Here's an example:

Consider a boat that's exactly like the one in the 000x drawings and add a 70# anchor winch and 50# bow-thruster to the bow (about 19' forward of the CG more or less).  The newly-added forward moment-arm of those items is 19' times 120#, about 2280 ft-lbs.  To counteract that, move the 100# of batteries that are right behind the aft house bulkhead aft to the transom and put the main motor on an 8" bracket (0.66 feet).  Assume the bracket weighs 40# and the motor weighs 500#.  Complex, but here goes. Removing the batteries from the house bulkhead reduces the forward moment-arm by approximately 3 feet (they were ahead of the CG by 3 feet) times 100#, about 300 ft-lbs.  This reduces the bow-down moment of the battery's original location by 300 ft-lbs.  Adding the batteries to the transom (inside the transom about 8' behind the CG) creates an additional bow-up moment-arm of 800 ft-lbs.  The net result of the battery move is an 1100 ft-lb bow-up moment change.  Now for motor and bracket.  Bracket is about 9' behind the CG and weighs 40#, a 360 ft-lb bow-up moment.  The motor's original moment-arm is 9' times 500#, or about a 4500# bow-up moment-arm.  Moving it to 9.66 feet further aft gives it a 4830 ft-lb moment for a net increase in a bow-up moment of 330 ft-lb.  The net trim change in bow-up moment is:

-2280 (anchor winch and bow-thruster) + 1100 (battery move) + 360 (added motor bracket) + 330 (motor move), or about a net -490 ft-lb bow-down trim.  Considering the boat likely weighs 5000+ lbs on the water, this likely won't cause a large bow-down trim.  Perhaps the original 2-1/2" bow-up trim becomes a 1" or 1-1/2" bow-up trim?  That would be fine.  But NOTE that if you used a 100# bow-thruster and a 150# big commercial anchor winch, their bow-down trim would become 4750 ft-lbs ... an increase in bow-down trim of 2470 ft-lbs ... a ton and a half!  THIS is why you really want to pay attention to WHERE extra weight is added and how well you've balanced it out.  Seemingly small decisions can make big differences.  This is because the GA is light for it's size ... making the boat half as expensive to build compared to one that weighs as much as a commercially-manufactured vessel, and giving you double the gas mileage so your boat can have an extended range and reduced cost of operation.  It's a fair trade.  A commercial 10k lb boat would not notice changes in the locations of items that a 5k lb GA would.

I retire as of March 1 ... high on my list is the creation of models and spreadsheets that will allow me to help builders dial-in their boat's layout in a most optimal way.  Also on the list is a fine tuning of the Standard and Kodiak GA's, now that they've been on the water for a long time and we can see what the typical usage is, designs around a slightly different weight arrangement.  NOTE that this will be a MINOR improvement in the designs ... the main issue in terms of trim is the boat's light weight combined with the fact that planing hulls have 2/3rds of their weight forward of the required CG envelope.  This is why live-aboard boats are DISPLACEMENT hulls rather than PLANING hulls ... a boat that's required to plane requires careful considerations and is by default more sensitive to things like weight distribution.  There are some beautiful live-aboard type accommodations in several GA's out there that demonstrate that it's possible.  You just have to pay attention and tune as you go.  Note that the Kodiak addendum document lists several ways to move the CG around should you need to.

20

Introductions - Are you new here? Say hello! / Re: Cruising focused GA 30

« on: November 03, 2024, 06:55:20 AM »

Hi Howie ... thanks for all the kind words!  When you say 28-feet "with swim deck", are you thinking of a 28-foot boat that has a swim deck that's just a deck, motor on a bracket? Or are you thinking of the 'extended hull' type swim deck in which the waterline is actually 28 feet PLUS the width of the swim deck, e.g. the waterline of a 30-foot boat but has a false transom at 28 feet and a 2-foot swim deck? Hope that's clear.  In any case, your plans sound great and certainly the GA can fill your needs and desires.  Ask lots of questions and we'll answer them (and likely give a lot of other hints along the way).

Brian

21

Projects - Glacier Boats of Alaska boat projects / Re: GA28 in Bakersfield California

« on: October 28, 2024, 08:20:53 AM »

Lookin' good!  When you paint the inside of the crash chamber (not req'd by the way), using white is a good idea ... if you store spare parts or tools in that space, the light-colored paint will help you see into it better.

As I've mentioned in the manual, if I recall, all bulkheads should have plug-able drain at the bottom of each ... you keep plugs in all of them when operating, but open all of them in storage ... plan to be okay with water getting everywhere.  Plug-able drains allow all water to drain out if necessary ... having several people in the house, or cuddy (the nappers ), or a pair of people sleeping in the cuddy can (likely) cause a little bow-down trim and if you've forgotten to plug the bulkheads before going to sleep, water can migrate forward.  Be ready for any situation.  This is also why I recommend a reasonable sill in the aft house bulkhead and it's also good justification for a cockpit deck that slopes downward towards the stern - even if the bow is down a couple of inches for whatever reason - good idea to design-in self-bailing concepts.  In a big heavy fiberglass or aluminum boat, the cargo (people etc) are a smaller percentage of the boat's displacement and have less effect, but in a boat such as the Great Alaskan that's built lighter in order to achieve higher fuel efficiency and to require a lot less (half!) the horsepower, the cargo is a larger percentage of the boat's displacement and you can expect trim changes as loads move around.

Brian

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Blood on the Deck! (And Other Grand Adventures!) / Re: First Antelope

« on: October 21, 2024, 05:17:28 PM »

Great buck and nice dead center shot ... did the bullet pass through the diaphragm?

23

General Discussion about the Great Alaskan / Re: My Official build thread. 27 1/2’ GA

« on: October 15, 2024, 05:24:04 PM »

I used exclusively Ebond epoxy.   I would use it again too.  Just want folks to be aware that I believe gasoline can cause issues with epoxy even if it doesn?t seem to affect the paint.  I?m sure that the gas was trapped behind the rub rails where it was allowed to do it?s evil, even though I washed the area every time the vents burped

Yeah, gas probably got trapped behind the rubrails.  I considered built-in gas tanks in a boat at one time, for more capacity in a given area, but decided not too.  While there were sealers that could be applied to protect the epoxy, but I was advised to just not do it.  I just now googled around and apparently there are 'modified' epoxies that are designed to be tougher, to resist petroleum products better (and the usual sealants are still out there), but all the descriptions say "resistant" not "proof".  Gas-resistant, even if pretty good, is not the same thing as gas-PROOF.  I think the best answer is to not put the boat away with super-full tanks ... as you mentioned.

24

General Discussion about the Great Alaskan / Re: My Official build thread. 27 1/2’ GA

« on: October 15, 2024, 07:20:19 AM »

I agree.  Marine epoxy is formulated for exposure to all-things-marine, including oil, gasoline, and other petroleum products ... but I also know that there are 'extra tough' marine epoxies out there (google it) that are designed to be even MORE resistant to damage from gasoline (etc).  That tells me that epoxy is not 'permanently resistant' to gasoline ... else why develop an extra tough version?  Or maybe that implies that companies selling the extra-tough versions have less than the best standard marine epoxy in their lineup?  Can't say.  The best knowledge comes from experience and that's one of the reasons for this forum.  What epoxy or epoxies did you use for construction?  For filling over-sized holes?

And yes, GelMagic is awesome and is formulated to be extra tough and to have extra-strong bonding characteristics.  It's an excellent choice for filling over-sized holes prior to drilling for fasteners.

25

Blood on the Deck! (And Other Grand Adventures!) / Re: Sekui Salmon

« on: October 03, 2024, 01:52:26 PM »

Is it legal to fish with a light?  If so, then I want the stern spot!

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Blood on the Deck! (And Other Grand Adventures!) / Re: Sekui Salmon

« on: September 29, 2024, 07:40:28 AM »

Nice!  Those are great eating size ... melt in your mouth tender!

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Blood on the Deck! (And Other Grand Adventures!) / Re: Sekui Salmon

« on: September 28, 2024, 10:46:54 AM »

Awesome!  Looks like the seas, weather, AND fish all cooperated!

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Projects - Glacier Boats of Alaska boat projects / Re: 13 Bananas New Jersey Kodiak

« on: September 20, 2024, 08:17:08 AM »

I love the full use of the space under the floor, and am curious how the hatches will be designed. Also love the FULL under-gunnel storage. Loving the craftmanship going into this one!

I was thinking the same ... and I'm impressed by all the fairing done on the accommodations!  It's going to be a beautiful boat!

29

Projects - Glacier Boats of Alaska boat projects / Re: GA28 in Bakersfield California

« on: September 16, 2024, 06:55:18 AM »

I think you're making great progress!  And those intermittent fishing trips aren't just for fun and delicious dinners ... they provide great motivation to get YOUR boat done ... important encouragement to keep a full head of steam until your boat's on the water.. Nothing like launch day!  And second to just that, your first fish in the boat!

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Blood on the Deck! (And Other Grand Adventures!) / Re: Headed to Sekui for salmon and Halibut

« on: September 10, 2024, 11:32:58 AM »

Sweet!  How ya gonna do better than that in bloodying up your boat!!?!!