Kevin Morin
Petty Officer 3rd Class
- Joined
- Nov 7, 2009
- Messages
- 78
Alaskan coastal rivers mouths provide ocean access for salmon 'runs', as they're called, with so many fish returning to spawn inland that they can be harvested commercially. Commercial fishing for salmon involves hook and line along the coast with Canada, called trolling, and almost everywhere else with gill nets. For those not familiar with that type of gear, it amounts to a nylon mesh curtain hung in the water with diamond shaped openings about the size of whatever species of salmon is anticipated or permitted in that region's catch. There are salmon seiners too, but this thread is about the rebuild of a welded aluminum skiff originally an 18' LOA salmon set net skiff used in the Cook Inlet to handle salmon gill nets anchored to the shore in tidal areas.
In order to look at the original skiff and understand her build, its important to think of a gill net as a huge wall of lace curtains otherwise the boat's structural elements will seem odd in the extreme. Handling a net that has been 'set' or placed on anchors in the water in the path of migrating salmon, is a matter of leaning over the bow, picking up the net's cork line that floats at the surface and then gathering the 12' deep lace curtain in your hands and pulling the entire bundle over the side of the boat. Once the cork line, web [net mesh] and lead lines [they make the curtain hang vertically] are all 'roped' into a 3-6" diameter bundle they are pulled along the top of the net skiff to the middle of the boat. When a gill net is over the skiff's amidships area the leads and corks are be pulled apart, fore and aft, to open the web allowing the crew to remove the fish.
Each crew member has to stand in the skiff, more or less facing fore and aft, holding the cork or lead line with their legs spread toward the chines on a relatively flat bottom and pull the net along - more exactly- the boat is pulled along sliding sideways to the net's ends. If fish are trapped in the web, 'gilled', by swimming into this nylon curtain from which they can't back out, they get pulled over the sides of the skiff and have to be 'picked' from the web and released into the bottom of the skiff.
One of the most important features of this type of boat is that salmon range from 3 to 75 lb. , depending on species, and enough fish in the skiff may add up to weigh more than the boat. In fact the sole purpose of using metal boats is the loaded skiff my increase wt by ten times.
If you add a following sea, a little surf to the gravel beaches where the fish are landed, and picture landing a few tons of fish on that beach; then, you'll be able to understand why the skiff in this remodel was built somewhat stronger than would seem needed. This type of commercial fishing may be done in sheltered waters or in more weather exposed locations so the boat has to carry the fish onto a beach in a potentially dry-breaking sea on a loose gravel beach. Most other boat building materials don't last very long in this service.
Suppose you needed to figure out how to build an open rigid boat weighing less than 500lb. that can haul three tons or more, is stable in a sea working nets, where all the structure didn't tear or snag the net anywhere? The upcoming pictures will explain why I built the original boat in the manner shown. The skiff in these pictures has ribs made of 0.125" sheet that are rounded along their bent edges forming hollow box beams once welded continuously to the bottom and sides. The sheer is lined with a full round pipe and the missing motor mount was surrounded by a slop tray of splash well to keep the side mounted outboard from the net when it was payed out over the stern. That is why this skiff is nearly flat bottomed but has 34-40" sides and a platform to stand over a very modest V in the bow.
If you're still with me, (?) I'll be explaining the reconstruction of a net skiff originally built in 1979 for net fishing salmon, which was converted to a college graduation gift for our daughter in 2004-05. I'd built the skiff when building full time, sold it but the owner offered it back in the late 90's for less than I could have re-purchased the metal, naturally I bought it intending to resell and 'make a killing'. Instead, I used the net skiff as originally built for a few seasons, just to burn gas, then leaving it sit on a trailer in the yard for several years; finally deciding it would be the quickest way to get a skiff for a graduation gift.
Unfortunately, I don't have any pictures of the original skiff before I put her in the shop and cut the transom out. Here, then, is the story of a Cook Inlet Salmon Set Net skiff converted to a [sort of uniquely shaped] runabout, with a stand up helm but remaining an open boat.
Using the aft most upright line of the topsides we can see the transom plane of the original skiff. The slop tray was cut out to the starboard and the full ht transom removed from the port.
A 1" pipe shaped like a hand rail but located about 6- 8" below the sheer pipe has been removed and the sanding marks to fair the former weld locations is evident along the topsides. This pipe was used to secure lines and hold on when the fishing, but won't be needed in this configuration in the remodeled skiff.
A two inch (2-3/8" OD) sched 40 6063 T6 pipe was rolled to the radius of the distance between the original skiff's beam at the sheer nearest the transom. The butt joint is about 8" forward the transom end of the original sheer pipes to use the topsides for support while the new form is tacked up.
With our point of view closer to the floor from the previous pictures we can see the lines of the rounded stern that will be hull extension create the new look. We're going to add a counter or a bustle stern and sometimes called a tugboat stern.
There was a boarding foot step on the transom that was a 2' wide bent of pipe butted to a pair of plates near the bottom aft. The listing waterline shows the engine was always off center and about what the skiff drew empty.
Looking aft across the starboard forward quarter into the cut out stern a sloped line is evident in the sanded topsides on the starboard side. That is the approximate outline of the splash well that kept the transom cutout from allowing a following sea into the skiff when surfing in to the beach.
In the image the ribs construction is more obvious- they're about 6" to 10" deep in 60" of span and almost all of them have a 4" to 6" flat top. These are all 0.125" 5356 bent on a sheet fold with a 1-1/4" diameter bead bar to insure there was no stress cracking in this bend and more importantly that if you fell on this box beam's edges you'd get bruised not broken. Also, this surface will NOT hang any web when it was worked side to side.
The ribs are transverse to stop a layer of fish from shifting fore and aft, which can plunge a bow or stern into the water. These ribs help with level flotation when swamped, although they are not adequate to that job alone, and they're very stiff but about as light wt as can be found for the combined weight of the final skiff. Being smooth sided they're easy on the crew when they slip in fish gurrey, so they're worth the effort to fit and weld.
Looking just a little closer at the bottom of the original skiff at the beginning of the remodel; the side ribs sit on the fully fit and welded bottom ribs. The bottom ribs have a 2" x 3" limber hole under them all to allow water's movement rapidly from rib set to rib set in order to level the boat if she takes a green one over the sides.
The limber holes are made of an extrusion of the shape shown that is cut and fit to the ribs before they are tacked down. When the fit is complete the ends of the limbers are tacked in the four corners to the bottom. By removing the rib used to locate the limber 'liner' a permanent full length weld can be placed along both sides of the extrusion where the legs lay to the bottom.
If anyone welds aluminum they realize these two welds will completely distort the bottom downward and the rib fit will be lost. Since the boat is cambered in the stern and transitions into a very light V forward, the fit of each rib is unique.
The method of regaining the bottom's originally fair form is to clamp the rib to the, now welded, extrusion ends. By putting large C clamps fore and aft the fitters can pull the heat contraction distorted bottom back to the rib's lower edges and the resulting added tension between these two elements actually increases the tensile strength of this alloy of aluminum.
A trial look at the new deck surface is being discussed by using the cambered plywood riser. Is that too much? will the deck drain if we make it less curved?
In the bow is a deck surface supported along its aft edge by a pipe that fits to the topsides just above the chine flat. There is a single leg to break that span and take the bounce out of the deck but there is no after bulkhead. In a more expensive and complete model of skiff this volume, under the bow deck, was used as an additional air chamber to contribute to the level flotation if swamped.
The chine flat is not full length in this skiff but only at the bow 1/3- 1/2 of the bottom. The flam is somewhat wide for a skiff this size but that is because of its purpose, smooth ride was not as important as load carrying and being able to get beyond the first few swells out to the nets.
The interior also shows the topside were convex as the edges of each vertical rib is curved outward. As the ribs are viewed for and aft its obvious the skiff's topsides have less lean out [flam] toward the stern as compared to the bow.
Cheers,
Kevin Morin
In order to look at the original skiff and understand her build, its important to think of a gill net as a huge wall of lace curtains otherwise the boat's structural elements will seem odd in the extreme. Handling a net that has been 'set' or placed on anchors in the water in the path of migrating salmon, is a matter of leaning over the bow, picking up the net's cork line that floats at the surface and then gathering the 12' deep lace curtain in your hands and pulling the entire bundle over the side of the boat. Once the cork line, web [net mesh] and lead lines [they make the curtain hang vertically] are all 'roped' into a 3-6" diameter bundle they are pulled along the top of the net skiff to the middle of the boat. When a gill net is over the skiff's amidships area the leads and corks are be pulled apart, fore and aft, to open the web allowing the crew to remove the fish.
Each crew member has to stand in the skiff, more or less facing fore and aft, holding the cork or lead line with their legs spread toward the chines on a relatively flat bottom and pull the net along - more exactly- the boat is pulled along sliding sideways to the net's ends. If fish are trapped in the web, 'gilled', by swimming into this nylon curtain from which they can't back out, they get pulled over the sides of the skiff and have to be 'picked' from the web and released into the bottom of the skiff.
One of the most important features of this type of boat is that salmon range from 3 to 75 lb. , depending on species, and enough fish in the skiff may add up to weigh more than the boat. In fact the sole purpose of using metal boats is the loaded skiff my increase wt by ten times.
If you add a following sea, a little surf to the gravel beaches where the fish are landed, and picture landing a few tons of fish on that beach; then, you'll be able to understand why the skiff in this remodel was built somewhat stronger than would seem needed. This type of commercial fishing may be done in sheltered waters or in more weather exposed locations so the boat has to carry the fish onto a beach in a potentially dry-breaking sea on a loose gravel beach. Most other boat building materials don't last very long in this service.
Suppose you needed to figure out how to build an open rigid boat weighing less than 500lb. that can haul three tons or more, is stable in a sea working nets, where all the structure didn't tear or snag the net anywhere? The upcoming pictures will explain why I built the original boat in the manner shown. The skiff in these pictures has ribs made of 0.125" sheet that are rounded along their bent edges forming hollow box beams once welded continuously to the bottom and sides. The sheer is lined with a full round pipe and the missing motor mount was surrounded by a slop tray of splash well to keep the side mounted outboard from the net when it was payed out over the stern. That is why this skiff is nearly flat bottomed but has 34-40" sides and a platform to stand over a very modest V in the bow.
If you're still with me, (?) I'll be explaining the reconstruction of a net skiff originally built in 1979 for net fishing salmon, which was converted to a college graduation gift for our daughter in 2004-05. I'd built the skiff when building full time, sold it but the owner offered it back in the late 90's for less than I could have re-purchased the metal, naturally I bought it intending to resell and 'make a killing'. Instead, I used the net skiff as originally built for a few seasons, just to burn gas, then leaving it sit on a trailer in the yard for several years; finally deciding it would be the quickest way to get a skiff for a graduation gift.
Unfortunately, I don't have any pictures of the original skiff before I put her in the shop and cut the transom out. Here, then, is the story of a Cook Inlet Salmon Set Net skiff converted to a [sort of uniquely shaped] runabout, with a stand up helm but remaining an open boat.
Using the aft most upright line of the topsides we can see the transom plane of the original skiff. The slop tray was cut out to the starboard and the full ht transom removed from the port.
A 1" pipe shaped like a hand rail but located about 6- 8" below the sheer pipe has been removed and the sanding marks to fair the former weld locations is evident along the topsides. This pipe was used to secure lines and hold on when the fishing, but won't be needed in this configuration in the remodeled skiff.
A two inch (2-3/8" OD) sched 40 6063 T6 pipe was rolled to the radius of the distance between the original skiff's beam at the sheer nearest the transom. The butt joint is about 8" forward the transom end of the original sheer pipes to use the topsides for support while the new form is tacked up.
With our point of view closer to the floor from the previous pictures we can see the lines of the rounded stern that will be hull extension create the new look. We're going to add a counter or a bustle stern and sometimes called a tugboat stern.
There was a boarding foot step on the transom that was a 2' wide bent of pipe butted to a pair of plates near the bottom aft. The listing waterline shows the engine was always off center and about what the skiff drew empty.
Looking aft across the starboard forward quarter into the cut out stern a sloped line is evident in the sanded topsides on the starboard side. That is the approximate outline of the splash well that kept the transom cutout from allowing a following sea into the skiff when surfing in to the beach.
In the image the ribs construction is more obvious- they're about 6" to 10" deep in 60" of span and almost all of them have a 4" to 6" flat top. These are all 0.125" 5356 bent on a sheet fold with a 1-1/4" diameter bead bar to insure there was no stress cracking in this bend and more importantly that if you fell on this box beam's edges you'd get bruised not broken. Also, this surface will NOT hang any web when it was worked side to side.
The ribs are transverse to stop a layer of fish from shifting fore and aft, which can plunge a bow or stern into the water. These ribs help with level flotation when swamped, although they are not adequate to that job alone, and they're very stiff but about as light wt as can be found for the combined weight of the final skiff. Being smooth sided they're easy on the crew when they slip in fish gurrey, so they're worth the effort to fit and weld.
Looking just a little closer at the bottom of the original skiff at the beginning of the remodel; the side ribs sit on the fully fit and welded bottom ribs. The bottom ribs have a 2" x 3" limber hole under them all to allow water's movement rapidly from rib set to rib set in order to level the boat if she takes a green one over the sides.
The limber holes are made of an extrusion of the shape shown that is cut and fit to the ribs before they are tacked down. When the fit is complete the ends of the limbers are tacked in the four corners to the bottom. By removing the rib used to locate the limber 'liner' a permanent full length weld can be placed along both sides of the extrusion where the legs lay to the bottom.
If anyone welds aluminum they realize these two welds will completely distort the bottom downward and the rib fit will be lost. Since the boat is cambered in the stern and transitions into a very light V forward, the fit of each rib is unique.
The method of regaining the bottom's originally fair form is to clamp the rib to the, now welded, extrusion ends. By putting large C clamps fore and aft the fitters can pull the heat contraction distorted bottom back to the rib's lower edges and the resulting added tension between these two elements actually increases the tensile strength of this alloy of aluminum.
A trial look at the new deck surface is being discussed by using the cambered plywood riser. Is that too much? will the deck drain if we make it less curved?
In the bow is a deck surface supported along its aft edge by a pipe that fits to the topsides just above the chine flat. There is a single leg to break that span and take the bounce out of the deck but there is no after bulkhead. In a more expensive and complete model of skiff this volume, under the bow deck, was used as an additional air chamber to contribute to the level flotation if swamped.
The chine flat is not full length in this skiff but only at the bow 1/3- 1/2 of the bottom. The flam is somewhat wide for a skiff this size but that is because of its purpose, smooth ride was not as important as load carrying and being able to get beyond the first few swells out to the nets.
The interior also shows the topside were convex as the edges of each vertical rib is curved outward. As the ribs are viewed for and aft its obvious the skiff's topsides have less lean out [flam] toward the stern as compared to the bow.
Cheers,
Kevin Morin
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