I have long dreamed of building a boat. Over the last 20 years or so I have explored the designs on Glen-L's website and one of these days I'm going to pull the trigger. It will be an I/O or jet. Would consider an outboard as well. The lake where I do most of my boating is large, but has some shallow areas to get from one part of the lake to another. The ability to be able to trim up and pass through these areas as well as trim up for shore landings is a necessity for me to enjoy this lake. I currently have an 18' bowrider I/O and its nice and comfy but its also heavy, sucks gas, and doesn't do anything well except look good. I used to have a 19' Baja with a hopped up 350 in it that was good for 60+ mph, but was also heavy and aging. Focus will be on speed, passenger comfort, and looking good. The chop never gets too terrible here. I have seen 3' chop on extremely rare occasions, but its usually possible with the shape of the lake to travel near leeward shores. Deadrise should allow for smoothing some chop, but it doesn't need to be offshore-levels of deep vee. Think maybe somewhere between a typical I/O and a flats boat vee.
Does anyone know of any boat design catalogs/websites I'm missing? Glen-L is nice, but most of their designs are from the 50s-70s
I'm also mostly here for ideas about power. The easy button is SBC, but I don't like easy buttons. This will also likely be a relatively light hull, and a 750-lb engine assembly isn't very attractive, particularly when it comes to CG issues. I have marinized a couple engines before and its surprisingly pretty easy. There are DIY ways of spark-arresting starters, alternators, and distributors. The big expense comes with fabbing jacketed exhaust manifolds and risers
So I'm thinking way off the rails here. Looking for a relatively small, light, power-dense engine. I doubt the hull I choose will be particularly deep, so to avoid big engine covers sticking up would be nice. Let's pick an arbitrary number of 300hp. Forced induction is ok, but not preferred. Chargers in boats are wonderful because with an endless supply of cool lake water, intercooler efficiencies can be well over 100%. Turbos are tough because you have to have water jackets before and after the turbo, but not through the turbo. That means either very difficult fabbing, or choosing off-the-shelf marine turbo parts which usually cost more than the boat itself and limits you to basically Chevy or Ford engines. Superchargers do get used in boats and are simpler to package, but given their belt-driven status they don't align well with the loads that marine engines typically see. Superchargers rock on the street because most of your time is spent between zero and 3/4 throttle. Marine engines spend most of their time between 3/4 and full throttle where supercharger efficiency isn't as good. Still a fine idea, just not as applicable as a turbo.
My initial thoughts:
- Suby 3.0L H6. My only concern there is that with the exhaust pointing down, it will be difficult/expensive to fab risers.
- I thought about a small V12 (who wouldn't want to hear the howl of a v12 through open exhaust?) but that adds tons of complexity to fabbing jacketed manifolds.
- Aluminum-block LS. Some jacketed headers exist out there but cost a fortune.
- I ruled out a Caddy 500. They're not particularly heavy (about the same as a 350) but they are just physically monstrous.
Help me think of some oddball ideas. As you brainstorm, keep this in mind: It needs enough displacement that the torque peak RPM is below cruising speed for two reasons. You don't want to "lug" the engine below torque peak while cruising, and if you don't peak your torque low enough you might never get up on plane. I've seen guys all excited to put a sport bike motor in their little Checkmate and then get disappointed when they have to lean forward over the bow to get on plane despite having 250 hp in an 800-lb hull.
