THE PADDLEWHEEL
Of all the systems which make up a Sternwheel boat, the paddlewheel is the one most frequently asked about. I guess I can understand this because it's the one component that no other type of boat possesses. Also, the paddlewheel is probably second only to the hull in importance on Sternwheel boats. Therefore, much study and research should go into the selection, design and construction of the wheel. Well, let's look at some paddlewheel questions.
What diameter wheel should I use on my boat?
Without going into a long dissertation about all the whys, my advice is to 'install the largest diameter that is proportional to your vessel'. Larger diameter wheels are more efficient and produce better speed. However, there are problems associated with driving large wheels so don't get too carried away.
How many buckets (paddles) should my wheel have?
There is more agreement on this point than most other aspects of wheel design. Most experienced builders, including me, say 'install one bucket for each foot of diameter plus two'. This rule works well for the size paddlewheels that most people will be installing on 'live-aboard' vessels.
How wide should my paddlewheel be?
This is a bit tougher question to answer. Wheel width is one factor which determines how much force a paddlewheel will produce. The amount of force required of a wheel is dependent on both, the weight of the vessel and, the efficiency of the hull. These values should be determined, as close as possible, before attempting to establish wheel width. Paddlewheel width is usually selected based on a percentage of the boats 'waterline beam'. Therefore, for me to select that percentage, I would need some information about the vessel in question. I will say that, under no circumstance, on live-aboard boats, should the paddlewheel have a width dimension greater than the diameter.
How wide (high) should my buckets be?
Again, this is a difficult question to answer. Bucket height is the second factor in determining the force that a wheel will produce. Therefore, it, too, is linked to the vessels weight and hull efficiency. Numbers here can range from 7 to 8 inches on small wheels to 20 to 24 inches on larger ones. A lot of boats in the 45 to 65 foot hull length range will use bucket heights of 14 to 18 inches. However, I must point out that this is just a 'guide line' and that an inch or two difference can greatly affect a vessels performance and power requirements.
How many spoke assemblies should my wheel have?
Most paddlewheels used on 'live-aboard' size boats should be built using three sets of spoke assemblies. Wheels 8 feet or less in width can be built with two.
How many 'rings' should I have on each spoke assemble?
Paddlewheel less than 8 or 9 feet in diameter can be built with only one ring providing that it is of adequate strength. Of course, larger wheels should have two or more.
Should my buckets be 'straight' or in a 'vee'?
Keep them straight. 'Wishbone' or 'Herringbone' paddlewheels are not worth the effort plus they do reduce backing and stopping ability. If you insist on using a 'vee', keep it small (like 15 to 20 percent of spoke angle).
What is the best material for bucket planks?
There are two schools of thought on this subject. One is 'cheap and expendable' and the other is 'tough and durable'. The first theory consists of using pine or poplar boards, either treated or un-treated and carrying lots of spares. The second (my favorite) consists of making the planks of 'white oak'. These should be kiln dried and soaked in some type of wood preservative before painting (red, of course). I don't recommend using stainless steel bolts to hold the planks on because of the possibility of creating galvonic corrosion between the bolt and the spoke. However, if you insist on using stainless bolts, you should also use 'locking nuts' or they will require frequent re-tightening. Using plain grade 5 bolts painted over works well because you'll probably have to grind them or twist them off to change bucket planks anyhow especially if you take my advice and use white oak.
How's the best way to build a paddlewheel?
I can't answer that question here. To formulate an answer would require certain knowledge about the wheels parameters and something about the vessel that it's to propel. Even with this knowledge, it would take pages for an explanation after the numbers were established. I can help, but you'll have to contact me direct. I will state that paddlewheel construction should meet two criteria. One, they should be strong. And two, their weight should be kept to a minimum.
Well, that's about all I've got to say on paddlewheels except that you should also look into 'placement' of the wheel. There's a bit more to it than just hanging it behind the vessel to satisfy the name "sternwheeler". Again, I'll try to answer 'specific questions' if you'll contact me at one of the addresses below.
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