Monthly Archives: November 2015

Shiny mold

Now that the plug has been removed from the mold, it has been polished to ensure a smooth surface for a smooth boat, plus make it easier to “pop” the mold and avoid the resin adhering to it.

Mold surface before polishing

Mold surface before polishing


Mold surface after polishing

Mold surface after polishing


Ready for the laminate

Ready for the laminate


Polished result

Polished result


We know what’s next!

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Next step, a boat

The plug has now been taken out of the mold, and I’m now looking for somewhere to store it as it’s my “insurance policy” if anything happens to the mold.

All the “boring” stuff is now complete and the next step is to make the first boat.

We are still contemplating which combination of composites to use for the construction. It’s definitely going to be carbon and probably 3 x 200 grams fabric. We are not going to use a gel coat as this is likely to add an additional 6 kgs, and the key construction criteria is weight. We are still in the resin dilemma of polyester or polyvinyl.

In the meantime, I’ve taken the opportunity to consider the differences between my boat and the Wenonah ICF C2. This boat is the only sit&switch ICF compliant boat available, and it sets the benchmark against which I will measure the Double Darkness (DD).

It’s difficult to find out a lot of detail about the ICF unless of course you own one. It seems to be quite an old design which replicates the style of the Wenonah C2 range, but with an almost “reluctant” acknowledgement of the ICF C2 regulations. It isn’t referenced on their web site and only appears to be available in the UK.

The ICF is completely open. It uses timber gunwales, and aluminium thwarts and seat fittings.

Wenonah ICF C2

Wenonah ICF C2


The DD was designed from the principles of a race boat, strict adherence to the ICF specifications, but incorporating the needs of racing paddlers. My boat is intended to offer a British alternative for DW and the longer canoe marathons.

The first criteria is weight. With 77 portages on the DW, it must be as light as possible especially if it is to offer female crews a viable option. I can’t find any definitive weight specs for the ICF, but a lightweight Wenonah pro-boat comes in at 15 kgs. As the ICF is about one metre longer, it surely follows that it will be slightly heavier. We are aiming for about 14 kgs.

The next consideration is cost. The ICF retails at about £3,400 which is a considerable chunk of change by any measure. I hope to come in at about £2,000.

So what about size and shape? I’ve taken some measurements of the DD, but I don’t have similar data on the ICF. However, I’ve traced the shape and overlaid it on the DD. It shows that:

1. The ICF is about 10 cms wider at the gunwales at the widest place.
2. The bow section pretty much matches the DD.
3. The rear section of the ICF is narrower than the DD.

DD dimensions and ICF comparison

DD dimensions and ICF comparison


So the front paddler’s access to the water is similar to the ICF, however the rear paddler has a few additional cms of width to overcome. The DD being a little wider, seems to offer more buoyancy at the rear.

The front and rear decks should offer better rigidity then the fully open ICF, plus these spaces will house the buoyancy bags. I’m not sure how or where buoyancy bags are secured in the ICF. The decks will also support the portaging handles, and the DD should be more comfortable whilst being carried upside-down on the shoulder.

The DD has a lower profile than the ICF and this is aided by the closed deck areas, as the water will simply run off rather than run in. The ICF has a higher bow to avoid swamping from washes.

The next comparison I made was the seating position of the paddlers. Whenever I’ve seen the ICF being raced, the paddlers always seem to be at the extreme ends of the boat. However, this is where there is least buoyancy. The rear paddler can get quite a long way back, but the front paddler is a bit restricted depending on the size of their feet, and there is no footrest.

DD/ICF comparison

DD/ICF comparison


If I compare the ICF, DD and a K2, I think I have a reasonable compromise whereby the paddlers are closer together than the ICF, but not as close as the K2, and they sit where there is maximum buoyancy. What I’m not sure of, is how high I can get the seats or how the boat will track and steer. The ICF has zero rocker, but the DD has a little towards the bow.

The rim around the cockpit of the DD is designed to reduce the amount of water coming into the boat, and also to support a full size stray deck. This will be quite a beast, with two zipped access areas. Most ICF paddlers tend to cover the centre of the boat with improvised sheeting. A self-bailer is a popular ICF accessory.

The most important part of the boat is the bit below the water line in terms of fluid dynamics and performance. The “trick” is to find the best compromise between speed and stability. This is mostly determined by the hull (wetted area) width and cross sectional profile.

The ICF seems to have a rather flat hull profile with hard chines. This affords good primary stability and as such, Marsport categorise the boat with a wobble factor of 4. This means that the seat height can be raised to (supposedly) deliver more efficient mechanical propulsion because the paddler can “get over the top of the paddle”. I have experimented a lot with this theory and have deduced that the benefits of a radically raised seating position compromises too much on stability. One advantage however, is that it is easier to get up from a raised seat than one which is too low, especially as one gets older.

Wenonah ICF C2 shape

Wenonah ICF C2 shape


The DD has slightly softer chines and a more rounded profile. It also has a more defined central “spine” towards the stern and bow.
Double Darkness shape

Double Darkness shape


There is only one sure-fired way to find out how this boat performs, and that is to get it on the water. I look forward with growing anticipation to this day.