Pic heavy post, and I found some of the finer points quite hard to explain. I hope you can figure it out and enjoy tying the fly. Then pack it when you hit the Breede.
Hook: Gamakatsu B10S x2, #4 or #2
Thread: Good old Danville 6/0, or similar. Strong, but not too thick.
2mm EVA foam sheet. That pasta flavoured foam is too thick and way too expensive. I bought the sheets I used in this SBS at PNA, and debut here the carapace made with so-called “brushed foam”. Looks pretty cool.
20 to 30lb braid, preferably not a bright colour.
Craft-quality superglue. I have used Cynobond V1 for years. You can glue a car to the road with it.
Optional: Suede chenille for making wee claws up front. The claws are optional but I like them. In the SBS I used the brushed foam to make them, because I didn’t have an appropriately coloured chenille on hand.
Also optional: Silicone to make the tail (actually the uropods and telson in the mud prawn).
Metal straight edge, craft knife with a fresh blade and a cutting board for making the foam legs and carapace
Material clips and a bank card (or similar) for making the Sculpting Fibre dubbing loop
Sharp-nosed tweezers for threading the foam legs.
Potentially iffy terminology:
Head: The front section of the fly, representing the thorax of the natural.
Carapace: The shell covering the thorax, in case of the ironman pattern it’s the triangular foam section that makes the top of the fly’s head.
Abdomen: The flappy, segmented bit of the natural, represented in turd patterns by the rear section of the fly. You can make this section as simple or as complex as you want; the silicone tail is cool but 100% optional, if not totally unnecessary.
Dress the hook from the eye down past the bend. Untwist the thread by spinning the bobbin holder anticlockwise, so it will lie flat when wound onto the hook shank. Then take the thread back to a point directly above the hook point. Coat all the thread wraps with superglue, let dry, and consider hidden rust a problem of the past.
To make a silicone tail, tie a bunch of sculpting fibre either side of the shank as shown, above the hook point, then fold the forward-facing half of the fibres back. Now smear silicone into this business, from the top of the base of the tail outwards. Work it through all of the fibres and mould the tail into a flat fan shape. Let it dry and then trim to shape. It’s not hard to bugger this up – I recommend some patience as you get the feel for it.
A quick Youtube search will set you up with some in-depth info on making dubbing loops and brushes, so I won’t go too deep into it here. Note though that all my dubbing brush/loop tools are homemade, including a dubbing loop spinner made from a stack of 50 cent coins, some glue, foam and wire. Not knocking the great tools available, but it definitely saved me a few cents. I work on a smooth table and use a card to shunt the prepared sculpting fibre over the edge of the table so I can grip it with a clip. Wrap the rest of the shank with the dubbing loop (or loops, in this case I used two dubbing loops to fill the shank completely).
Trim the concoction to shape using some sharp scissors. Taper it a bit from the joint to the back, and trim it as flat as possible. Done with the back-end.
I only mention it now, but it’s handy to have the following bits done before starting the fly. Cut a triangular piece of foam for the carapace. For the standard #2 B10S hook, the triangle should be roughly 35x18mm. Slightly smaller for the #4 – I haven’t measured it yet. Cut the legs roughly 1,5 to 2mm thick; the “2mm” sheets I use are usually thinner than 2mm, which is ideal. I eyeball the cuts , which means I get some variation. I use the thinnest strips for the first and last leg I’ll tie in, the thickest ones for the second, and whatever size in between for the third and fourth. If yours are all exactly the same thickness, great stuff and no worries. Lastly you need to cut a thicker piece of foam (5mm thick or a stacked and glued 2mm) to a long triangle shape that will fit inside the head. I usually cut this piece just before gluing it in, to make sure I get a custom fit. This little piece plays a big part in making a solid, durable fly, as well as in creating the final shape.
I cut a bevel into the end of the carapace triangle foam part to reduce bulk when tying it in. The inner edge of the bevel also provides an indicator of where the thread will go when you tie it in. Damn I hope any of this makes sense. Moving on.
Now connect the two hooks using the steps shown in this wordy Gas Hed Prawn SBS. Seat the loop holding the back hook just past the hook bend, and don’t make the loop too big or too tight.
Fold the carapace triangle in half lengthwise around the front hook shank and trap it in place, using the bevel line in the foam and the hook point as guides. Make sure that the connecting loop allows free movement on the back section, but that no hook shank remains visible between the carapace and loop.
Invert the hook and tie in the legs from the back towards the hook eye. I use only a single v-wrap (an x-wrap but with the centre of the x at the back edge of the leg strip) to secure each strip. I try to tie the strips in as snug as I can, using the minimum space on the shank to attach all five strips. Then take your thread to just behind the hook eye, using touching turns. Tie in the little claws if you want them. I like chenille for this, but used foam here to match the carapace. Then tie the front leg strip down in the same spot, on either side of the shank, leaving a bit of space for the rest of the legs to fit between these legs and the shank. It’s important to use the minimum thread wraps throughout the fly to avoid bulk building up and, well you know, ruining everything.
Snip the minimum off the remaining legs to get them to the same length. If you don’t do this, you’ll battle achieving symmetry in the following steps.
Starting with the back pair, fold the leg strips under and thread it through the slots created by the front legs, from the bottom up with the hook inverted as shown. You’ll want some fine tweezers for this job, and you’ll find fitting the last pair quite a faff. Once they’re all threaded up, use the tweezers to tweak them into alignment.
Now, starting from the front pair of legs and moving back, pull each consecutive pair just snug with the one before it. I grip both ends of the pair of legs in the tweezers at once, and pull up while keeping the rest in place with my left hand. This helps keep things symmetrical, although I usually need to do some tweaks to get it just right. With the exception of the back legs, pulling the legs just snug against the pair before it is usually enough to get close to the desired arrow(ish) shape. The back legs get pulled a little tighter to round out the back edge of the head section a bit.
Cut a small filler triangle (henceforth the “inner”) to fit inside the head, and glue it in. I use a drop of superglue front and back of the hook shank, and try to be quick about getting it done. It may squeeze down the legs a little, but I deal with that like so: Once it is glued in, apply another drop of glue to the sides of the inner, and push the legs into it by squeezing from below on both sides, using your thumb and forefinger. Press a little harder near the front of the head to taper the arrow shape a little more. Again, get it done as quickly as possible to avoid the glue drying before the legs are properly attached. And again, I hope this makes sense. After this step the legs aren’t going anywhere, so make sure you have them positioned nicely before gluing them. Then trim the inner so it lines up with the legs when viewed from the side.
Pull over the carapace, secure with only two tight wraps and tie off, then trim off all excess foam. I’ve come to like leaving a small point over the hook eye. Use a needle to apply a drop of superglue to all visible thread wraps. Now, to add structural strength and seal the head from soaking up water, dip the needle in superglue and quickly run it along the seam between the legs and carapace, and then between the legs working from back to front. Get it done as quickly as possible to avoid gluing the needle to the foam. Perhaps I should try a gel superglue for this? Either way, that’s it.
In the next few parts of the series I’ll look at some more crab, prawn and shrimp patterns, specifically what I consider the simplest to tie, yet effective and therefore simplifying fly choice as well. I’ll drop another SBS or two , too.