What is Rotational Molding?
Rotational Molding (sometimes shortened to rotomolding) is a plastic process for manufacturing usually larger plastic items. It is not a new process as it has been around for over 50 years, but it is only in the relatively recent past that mold makers have developed the technology to make molds sophisticated enough to manufacture something as complex as
a boat; in the past it was only possible to make simpler shapes like agricultural tanks, water tanks and less complex toys.
Rotational molding is basically a process in which a predetermined amount of finely ground plastic material (usually polyethylene but not always) is put into a hollow metal mold. This mold (usually two halves but sometimes made with 3 or more major parts), with the material in it,
is put into an oven/machine which heats the mold, while at the same time rotating it around two or more axes. As the mold rotates on these axes the heat melts the plastic material which adheres to the inside of the mold. When all of the plastic has melted and adhered to the walls of the
mold the mold then goes into a cool-down process. Then the mold is taken apart and the newly formed part is removed. This plastic part is hollow on the inside as the amount of material originally put into the mold does not completely fill it.
The rotomolding process, because it makes parts which are hollow, combines simultaneously the bottom outer part (hull) together with the topside (cockpit and deck). This means that not only are the top and bottom parts made at the same time but that no subsequent process is required to fit and attach them together. Compared with other boat
manufacturing processes this is a large time saver, and since the rotational molding cycle can take less than an hour the manufacturing economics are positive. There is of course, high capital investment in the machine and mold(s) but the process is repetitive with minimal equipment maintenance.
Polyethylene as a plastic material is not new as it also has been around for over 50 years. As a material it is produced in a variety of formulations and is used to make common everyday products such as food storage containers, bottles of all kinds including the common every day milk jug. As such, one of its most important characteristics is its
impact resistance – items made from polyethylene seldom break when dropped or are impacted by other items. This gives a boat made from polyethylene a big advantage in the rough and tumble world of marine use. However, because it is relatively soft polyethylene does scratch easily. But because color can be blended into the material itself incidental scratches are not as unsightly as they are in the gel coat or paint of fiberglass.
We are frequently asked how punched through holes are repaired. Fortunately this happens so seldom that it is not a big problem. A hole can be repaired, however, by “welding”. It does require a special plastic welding tool (we have one in our shop) but we have never had to repair an accidentally punched through hole; instead we use it to
repair manufacturing defects such as holes that inadvertently get drilled in the wrong place.
As excellent as polyethylene is as a boat manufacturing material it has its trade-offs. Because polyethylene is not as stiff and hard as say metal or fiberglass it is frequently not sturdy enough to take concentrated loads. Highly concentrated stress points of things like screw locations or supporting attachment points have to be considered carefully. Rotomolded part engineers frequently call for metal fasteners to be molded into the plastic part as stress location terminals. There are also other design ways of dealing with high stress areas such as distributing the loads over a single wide area or over through several
points instead of just one. Also, metal screws in a material such as polyethylene have better holding power if long screws with many threads are screwed into material thick enough so a lot of threads are engaged.
Because Nauticraft has its own rotomolding machine and is committed to the process for making our boats, we take advantage of this position to design and rotomold ancillary parts such as the seats, pedal drive units, rudders, and steering handles as well as the Escapade windshield arch.
These smaller molds are mounted together on a ‘unit frame’ which enables them to all be molded at the same time. This makes it convenient for the production of these very necessary parts.
Polyethylene is also relatively inexpensive as boat building materials go. It is also light in weight, having a density less than water itself. This means that a polyethylene boat in a catastrophic mode of being filled with water will still float unless weighted down by something heavy. This is psychologically a big advantage to those of us concerned
about safety out on the water.
Can I adapt your drive system to my kayak or canoe?
Our drive is quite specifically designed for our boats. However, we do sell our drive system separately for $500 each; this includes the prop up to the pedal drive. To adapt to other boats will take more then average handyman skills. There are other systems more appropriate for adaptation then ours, see our links page for ideas.
Can I camp on my boat?
Not much room for camping, but plenty of room for gear!
Can I add a sail to your pedal boats?
Although we don’t recommend or offer a sail for our pedal boats- we certainly encourage you to personalize your Nauticraft boat, keeping your safety in mind. We have seen owners experiment with a sail on the Escapade, see our links page for info.
Also, check out our new sailboat, the Tribute- a 13′ rotomolded sloop rigged classic sailboat for the sailors out there!
Can I replace your pedals with my clip-on style pedals?
No problem, the pedal crank arms are standard bicycle parts and will accept most pedals.
Can I add navigational lights for touring at night?
Yes, we recommend you visit your local marine store(West Marine, etc) and ask for portable nav lites, or give us a call and we can supply you with a set. We have found that the LED lights have much longer battery life.
Can I paint stripes on my boat?
Polka dots, zebra stripes- you name it! We have found that Krylon “Fusion” spray paint bonds well to plastics and is available at most home stores and super stores.
How can I mount my fishing rod holder to my boat?
We use standard sheet metal screws (stainless steel) size #10-#14. You can screw directly into the plastic hull- but it is best to call us to be sure you don’t screw into a hidden part within the cavity.
Can I cut holes into the boat for storage?
We don’t recommend this, but if you plan on cutting into the boat, call us first for advice on the area you plan on cutting into- you don’t want to weaken the boat or cause a leak!
Can I mount my outboard motor to the boat?
There are no provisions for mounting an outboard motor, and the boats are not Coast Guard rated for propulsion by auxiliary motors of any kind.
How will my boat be delivered to me & what should I be prepared for upon its arrival?
We contract with third party shippers to arrange for the shipment of our boats. The shipper picks up the boat directly at our factory to be delivered to you. We recommend that your boat be delivered to a marina as they have the means to remove the boat from the truck and get it in the water for you (i.e. loading dock and extension forks for the fork lift). If that is not an option for you, the boat may be delivered to your place of residence and we will provide for a lift gate. Even so, because the boat is such a large package (137 inches – 174 inches in
length (depending on the boat you purchase)) it will require some steadying as it is lowered to the ground. We suggest having at least 3 – 4 strong able persons to assist you with the removal of the boat.
Keep in mind that the boat is delivered in a box. You will need a means of getting the boat from the box and into the water. Whether that is via one of our trailers or possibly the launching wheel set (for the Encore, only, and assuming a concrete boat ramp), you will need to plan accordingly.
Can I pick up my boat directly from the factory?
Yes, most certainly. We suggest also purchasing one of our modified trailers (i.e. modified for the Encore & Escapade boats so as to fit the keels on those boats) for ease of transporting the boat.
Do you ship boats internationally?
Yes. Please contact us for a quote.