REGULAR READERS WILL BE AWARE of my predilection for Mares Plana Avanti Quattro fins. When it comes to performance and price, I have found them to be the fins to which all others can be compared. They have become an industry standard. Dive guides the world over have taken to them by storm.
They are lightweight, sufficiently robust, supremely comfortable and very effective, especially when the chips are down and you simply have to go for it. Of course, there are better-performing fins, but only just. There are lighter fins, but not by much. There are cheaper fins, but not as effective.
So Mares should be happy, shouldnt it Well, not if it has to keep ahead of the competition, and the competition will always strive to market something that has better-perceived advantages. The buying public is fickle, too.
We get bored with same old, same old. We want same, same but different.
So the designers at Mares have given themselves a problem.
They produced a split-bladed fin, the Raptor, for the US market, and it seems you can no longer sell any other type of fin to Americans.
Despite what people say in Europe about split fins, Raptors were excellent - but over here the reputation of the split fin seems to have been trashed.
So Mares had to ask, with what should it replace the ageing two-material Quattro design The technical boffins in Genoa have been working hard to come up with an answer, using a third technopolymer. The X-Stream is currently it.

Blade
Lay an X-Stream on top of a Quattro, and youll see that Mares is sticking by exactly the same blade dimension as before.
Its a paddle fin. The Quattros got the scooping effect by letting in four flexible channels to the otherwise rigid blade. The X-Stream uses a very flexible centre section surrounded on three sides by an extremely rigid support of strong side-bars and the foot-pocket.
The blade has some vent holes let into it with the aim of keeping the flow of water running close to the blade, and producing less turbulence and fewer negative vortices.
There is even a slight pivoting effect at the foot-pocket that emulates the older Mares Volos. The designers have dispensed with those parts of the blade that do not contribute to thrust.

Foot-pocket
The foot-pocket of the Quattros in size XL was made for my foot and a pair of ONeill boots.
Although Im sure that the company made them a little shorter than the originals, which encompassed my foot right up to and including the heel, the Mares people steadfastly deny it.
The foot-pocket of the X-Stream fin is made to exactly the same dimensions, but from a different material. It seems less flexible than the compound of the Quattros at first glance, although Im sure it isnt.
Those of you with smaller feet might have suffered a loss of performance due to a parachuting effect of water rushing into the available space in the foot-pocket as you finned forwards.
X-Stream fins counter this with a basket-weave effect. It looks a bit like those jelly-shoes you can get for wearing on the beach, and allows water simply to flush in and flush by.
I dont suffer any of these problems when wearing a drysuit. The boots of my OThree
suit fill the foot-pocket of any fin I wear. You know what they say about mean with big feet... (Big head Ed)

Straps and Buckles
Typically, these Mares fins come complete with the Mares ABS or Advanced Buckle System. These allow you to cantilever your fin-buckles tight (you can do it with the opposing foot if youre clever), thereby keeping the strap at optimum adjustment.
I liked this system when the company first produced it, but now I find the improved version difficult to release, and have broken lots of water-softened nails in the process.
I would replace these buckles with stainless-steel spring straps if they were mine.
That said, the other day I was putting my fins on in a RIB when one of these indestructible stainless-steel straps broke. Theyre not meant to do that! Amazingly, I had put a spare in my bag before setting off on the trip.

Efficacy
The first place I used these X-Stream fins was in Wraysbury Lake. No challenging conditions there, you might suggest.
However, during a long surface swim on my back across the lake, I noticed that the upwellings of water from my finning efforts were appearing powerful, and yet affecting the surface a long way from where my fins ended.
This augured well for some good effect when getting my head down in an oncoming current.
These X-Stream fins could be the worthy successor to the Quattros. They weigh in at around 200g less per pair, which is good news when travelling.
What a pity they simply dont look as sleek and sexy, and theyre certainly not cheap!

COMPARABLE FINS TO CONSIDER:
Scubapro Seawing Nova, £129
Aqua-lung Technisub Slingshot, £120
Atomic Splitfin, £125

SPECS
PRICE £125
SIZES S, R, XL
COLOURS Yellow, blue, red, black
WEIGHT 1.77kg per pair (size XL)
CONTACT www.mares.com
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