Show Posts

This section allows you to view all posts made by this member. Note that you can only see posts made in areas you currently have access to.


Messages - Brian.Dixon

Pages: [1] 2 3 ... 186
1
High Justin - good questions!  The biggest thing to keep in mind when comparing the Great Alaskan to the 'tug' cruisers, is the type of hull and what the trade-offs are.  There are 3 types of hull / boat designs in the world:

Displacement Hull - These just push through the water and are limited, hydrodynamically, to "hull speed".  Hull speed is the maximum speed the hull can travel through water without having to use exorbitant amounts of power, e.g. realistic powering limits.  The hull speed is 1.34 times the square root of the waterline length. Assuming a 29' waterline length on your tug, the hull speed is just 7.2 kts.
  • PROS: Super efficient, large load capacity, maximum cubic footage inside the boat (deep hull)
  • CONS: Slow, typically more expensive to build (there is a strong correlation between ship weight and cost to build ... think "dollars per pound to build this boat". Best efficiency is at half hull speed or slower.

Planing Hull - These hulls plane (skip across the top of the water) when travelling above their minimum planing speed.  The Great Alaskan series of boats are true planing hulls capable of high speeds.
  • PROS: Modest efficiency, lowest cost to build (lightest boat style), and fast!  Speeds on plan can range from around 10 kts to over 50 kts, depending on the boat's design, loading, and power.  Efficiency while on place is moderately high, higher than semi-displacement hulls but lower than true displacement hulls.  Planing hulls have the least cubic feet of interior volume due to more modest deadrise (the 'V' in a V-hull).
  • CONS: Least payload or carrying capacity of all, strict requirements on where the longitudinal center of gravity (LCG) must be located in order to plane with no bad habits or characteristics.  Very little flexibility in the payload and weight distribution in the boat due to the LCG requirements (LCG must be within 60% to 65% aft of the forward end of the waterline when in use). If you need more volume or weight capacity, then build one of the larger versions of the Great Alaskan.

Semi-Displacement Hull - These hulls are best described as a deep-hull planing hull that is too compromised in it's design to be able to achieve true planing.
  • PROS: High efficiency when speeds are limited to those described for displacement hulls (above) - a good work boat where most of the day is spent taking care of slower tasks (lobster boats etc).  Able to achieve faster speeds than a displacement hull since the boat can partially rise on plane, e.g. faster getting to/from port and the fishing grounds.  High payload capacity, although typically not as high as for true displacement hulls.
  • CONS: Only efficient when travelling slowly.  When partially on plane, e.g. "semi-displacement mode", this hull is the least efficient of all - the one and only advantage is it's higher speed than a displacement hull.

So ... given the explanations above, the answer for you is yes, you can use the Great Alaskan as you describe, but there ARE strict limitations on weight placement in the boat, and to a slightly lesser degree, limitations on how much weight you can put in the boat as well.  Given a basic, as-designed for typical usage, boat - additional weights added to the boat on either side of the LCG must be balanced out by an equivalent "moment" on the other side of the LCG.  A moment is the moment-arm (distance) times the weight of the item.  Gobble-dee-gook ... Best described with an example.  The Great Alaskan comes with a drawing(s) that show typical placements of motors (and their weights), fuel tanks, appliances, storage etc that show the 'expected' way to fill the boat with what you want in it.  The LCG is shown in the drawing (TBD - not added yet).  As a realistic example, if I add a 30 lb load, say a refrigerator, at 10 feet forward of the LCG, that creates a bow-down moment of 30 lbs times 10 feet, or about a bow-down moment of 300 lb-ft.  To balance the boat, I would need a moment of 300 lb-ft behind (aft of) the LCG.  For example, placing a 60 lb weight at 5 feet aft of the LCG would create a balancing bow-up moment of 300 lb-ft (60 lbs times 5 feet) and the LCG would stay in the same exact location.  To balance that refrigerator, I could perhaps locate the house battery near the stern of the boat ... or I could use a longer motor bracket or a heavier motor, or add a kicker motor if there were not already one on the boat.  Simple, yes?  LOL. 

The best idea is to try to keep the apple close to the apple tree and use the given layouts as a general guideline, and look at trim versus weight placements from what others have done.  You can of course ask me for guidance, and post questions in the Builder's Forums (the BEST idea) at https://www.glacierboats.NET .



2

Nice fatty! :D


3
You can use airbags with StableLoads but they recommend no more than 50% of suggested air.

Here is some info: <snip>

Good point on how the airbags work, how the effectively transfer load away from the truck's suspension and instead concentrate it on the airbags.  I think most airbags require a hole being drilled into the frame too, and if the edges around the hole aren't deburred properly, then the frame can crack across the area where the hole is ... I knew someone who had this happen.  I've never been, at least without a lot more research, highly in favor of airbags.  The StableLoads transfer load from the main leaves to the overload leaves 'early', more or less making the whole stack work together right from the start ... that sounds good to me.  And the StableLoads can use wedges to help lift one side of the truck more than the other, e.g. to level out a truck who's load makes it lean to one side more than the other - like when hauling a 5th-wheel that has slide-outs on only one side (extra weight).


4
Oh,

The scuppers, no water came in even with waves slamming the stern, my nephew is 300lbs, even with 3 people at the rear, nothing!   ;D ;D ;D ;D

Great news!  How much (fore and aft) did you raise and slope your cockpit deck?


5
Awesome!  Great trip ... I'm jealous!

Can you use airbags together with the torklift stableloads?


6

Welcome aboard!  I speak for all when I say we are looking forward to your progress, pictures, and questions (which help everyone as well)!

Brian


7

Navigate to https://www.GlacierBoats.com and click the 'buy' link for metric OR imperial study plans - FREE check out!  The price will return to normal, $5, on October 1st...

NOTE: 'Buying' free study plans will also notify me so I can permanently activate study plans downloads from our website for you (requires registration and login to download)

8

Wow!  You're definitely living the dream!  Taking the time to do such a complete and beautiful job on your Kodiak is really paying off ... fantastic pix too!  Soooo jealous!!

(And thanks for the kind words!)


9

Wow! Very pretty!


10

Very neat work!  Keep it up!  You're almost done with all the squirrelly places that are hard to reach!

11
Ah, got it. Thanks!

I wish I could figure how much "better" this would be with regards to puncture resistance to see if it is worth doing. The kevlar would be about $400 to do the entire bottom assembly. Could be relatively cheap insurance or totally unnecessary.  I should probably do some sample panels both for figuring out the application and doing some destructive testing in the backyard.

So far, nobody's managed to puncture a Great Alaskan.  How necessary the kevlar is, is anybody's guess.  The standard 3/4" (18+ mm) thick bottom with 10 to 20 ounces of glass sheathing on the bottom is pretty darn tough.


12
scarf/cut bottom panels 15mm aft, 9mm fwd
while flat, laminate 5oz kevlar with 6oz fg on top
same with 15mm chines
stitch panels and chines and fillet/reinforce with fg tape per plans
Once bottom panel assembly is set to stringers add 2nd layer of 6mm ply to fwd bottom

Almost!  If you examine the original build instructions, you will see that a layer of 10-oz glass is added to the entire inside surface of the bottom panel assembly after the seams are complete.  In your build order below, you are effectively doing all of the interior glassing prior to assembly, but the seam layers are added after that ... the seam itself, in terms of glass over the seam, ends up short since you are not doing final interior glassing over the top of the finished interior seams.  I'd add one more 10-oz strip of tape (2" wider than the previous) over the fairbody and chine seams.  Like this:

scarf/cut bottom panels 15mm aft, 9mm fwd
while flat, laminate 5oz kevlar with 6oz fg on top
same with 15mm chines
stitch panels and chines and fillet/reinforce with fg tape per plans
apply 10-oz tape over the fairbody and chine seams (on top of the fillet/glass applied in the previous step)
Once bottom panel assembly is set to stringers add 2nd layer of 6mm ply to fwd bottom


13

It's definitely worth it from a puncture perspective, in my opinion, but I've known several people that cussed kevlar after trying to put it in.  I would do a couple of 2' by 2' pieces of ply first, to see if it works for you and/or to get some practice, then do the boat.  And I'd expect a few shallow bubbles here and there too, but after the kevlar cures, then drill holes on each end of the bubbles and use a syringe to inject epoxy into them. You can use masking tape over the holes to keep the epoxy from draining out.  I don't think putting kevlar on flat panels is terribly difficult, but it probably just benefits the project to have a little practice first.

One thing to keep in mind about kevlar is that it absorbs water if exposed to it, but that's one of the reasons we don't put it on the outside of the boat ... gouges may expose water to the kevlar, and freezing temperatures may start some delamination.  If you put it inside the boat, and especially with the 6-oz glass over it, then bob's yer uncle...


14

Since the original bottom ply thickness was spec'd at 5/8" (16mm), I would not use plywood that is only 15mm thick.  You can, but then I'd want you to add an additional layer of 10-oz glass on the inside of the bottom panel (and chine flat) assembly ... or at least 5-oz kevlar (aramid) over the whole length.  Since I'd want this extra glass over the seams, you'd have to add the kevlar to the inside faces when they are flat and unassembled, then after assembly, go back and add an extra layer of 10-oz glass tape over the seams ... to meet or exceed my requirements.  You'd lose your weight advantage, but not all of it. 

15

For cracks and crevices, I vacuum them to pull dust out as necessary. Compressed air works, but to prevent impacting dust in the nooks and crannies, I vacuum first.....

Looking good!


Pages: [1] 2 3 ... 186