“A Wharrl! A Wharrl!”
Captain A.(it´s Abraham, I think) Happ of the Navy of Murash is obsessed with the idea to hunt down and kill the critter that bit off his... but that story has already been told elsewhere.
Only one thing: “Wharrl” is made up of “whale” and the pirate´s “Arrrr” (see any PotC for reference). In german at least it is instantly recognized and even sounds funny.

2007, Murash- Orga ( http://murash.phoenix-carta.de ).
The “Murash goes sailing”- conventions take place on the three-mast- schooner  “Pippilotta” in the baltic sea. Of course then the silly name is dumped and she becomes the “Elucidation”.

The job was: Build a Sea Monster (the white wharrl) with the following attributes:
- it has to be able to swim in the baltic sea where it is steered by a puppeteer invisibly swimming under it
- it has to be able to eat a second human who then vanishes from sight under the monster together with the puppeteer.
- it has to have a “breathing hole” into which a harpoon  will be stuck
- it has to be easy- to-transport and must be able to be launched quickly from the mothership.

These guys are insane. 

The low-budget-sunshade is lightweight and a little broader than  a car´s roof. You won´t get a cheaper chassis. Saw off the shaft and secure the folding- slider with a screw.
Buy 3 low-price air- matresses (one as reserve). Blow them up only a little so that you can still roll them, do so and measure the circumference of the coil.
Sew two cloth tubes of the appropriate circumference onto the sides. The sewing machine has to stand freely for this operation while the sunshade is held upside down by two helpers.
Fit in the two rolled air- matresses. Voilà.

Overlay the surface of the sunshade with cheap foam- matresses (doesn´t have to be black because the monster won´t be beaten with foam- weapons). Glue: Pattex. Carve a lot of foam- spikes. Tell the players not to jump onto the monster from the ship (you never know what players will do to solve a plot).
Above: Swimming-test. Each air-matress will carry about 20 kg. The upwelling is sufficient.

Above: It doesn´t weigh much. At the front there is an opening for the “helmsman” to see through while steering it, all the while swimming under the construction.

Above: What does the surface of a seamonster look like? Thanks to everybody who without objection have carved a lot of isolating-tube-barnacles so that the artist could concetrate on applying them. Such work (or grounding) are tasks that´ll take forever without help.

Above: Banacles, more spikes and a big, jagged fin that can be removed for transport; see below. The foam- plates of the back aren´t glued to the sunshade in the middle where the fin is, they are loose on the chassis each about one hand´s breadth from the spine. Because of the curvature of the back they don´t fold up. The fin´s underside follows the curvature of the back and has a t-shaped basis. Stick base under back-plates and it´ll hold.

Above: Black grounding with acrylics. I love the moment when the paint causes the different materials to vanish and a homogeneous surface appears. Step back a moment and enjoy.
At the front are finlike jaws similar to the ones a ray has- only with teeth. The “breathing- hole” is surrounded by foam and the center back seam is completely invisible.

Above: White. Not pure white but shaded with black.
What colours should fin and barnacles have? We decided upon pastel- flesh and pastel- green so as not to create a too big contrast to the “colourless” colour white. A difficult decision after some unsuccessful attempts.

Above: Finished. Looked gigantic in the garden, less so in the baltic sea. But building it bigger would have been unreasonable.
And if ever something like this emerges in my swimming pool I´ll see to get out of the water as soon as posible.

Ways to improve it:
To make it appear bigger one could have added a detachable tail with implied half tail-fin protruding from the water. 1-2 more working- days though...

Above: Detail of the back fin assembled and removed.
The non-glued parts of the back can be bend outwards enough to take the fin´s t-base in spite of the paint.

Above: The bottom side with rolled up and inserted air-matresses. The backside is open to better let water stream through it.

Above: For a proper wharrl- hunt you also need nhorrmal wharrls. This here is a blue wharrl (on the left the top side, on the right seen from below).
A blue wharrl is about as big as a norrmal cheap umbrella with sawn- off stick and screwed- tight slider that somebody has glued cloth and foam- spikes on, then painted it with acrylics...
Never use only one colour- the “blue” upper side for example is not blue at all but shaded blue/ black.
The 2- part-bottom is designed to host a cheap bathing ring to keep the thing on the surface after being thown overboard. The plastic- strips hang out from the middle for a jellyfishlike touch.

Petri hail!*
*= 500- year- old german expression for “Good fishing!”