|Build Your Own Raceboat|
Questions from Builders and Prospective Builders
Cleaver for Pro Tunnel?
"Any ideas of where I can get a good cleaver or racing prop for my 1988 johnson 25-35 hp, surface prop."
Ron Hill in California has worked with us, even gave some props to our GT Pro class (see above). I bought a cleaver from him in 2010 (pic above). A little undersize at about 9.75" diameter (pitch is 17"), and needs more cup, but I had my tunnel (since moved up to Sport C) going 49 mph at 7000-7200 rpm with this prop. I plan to... add a little more cup and whatever else it may need. I think it will work well on my new boat (EZ Tunnel, built in 2011).
"We race 25hp-35 hp mini boats here [New Zealand], what is your fastest hull out of your boat plans?"
Fastest boat is probably the Pro Tunnel with its 42" wide tunnel. The new EZ Tunnel is also fast, but with 40" tunnel probably not quite the potential, especially with 25hp.
"Me and my son are thinking about building a speedboat with the possibility of competing in the GT15/GT30 class racing. These classes race with a standard EPA-certified outboard in either 15 (10 to 16 YO) or 30 hp (14 and up)
"The boats are V-bottomed monohulls of minimum 3.5 X 1.3 meters (11.48' X 4.27') with a minimum weight of 210 kg (463 lbs) with a 15 hp and 250 kg (551 lbs) with a 30 hp outboard, full rig including driver.
"Would the Pro Vee be suitable for these classes? I have tried to calculate full weight but I really have a hard time estimating what the added weight to the bare hull will be. All my calculations tend to end up on the heavier side though"
I am currently racing a Mini Vee in our GT Pro class, which has a minimum weight of 650 lbs. Actual weight of my boat, after racing, is about 655 lbs. I carry 45 lbs. of ballast. We also use hydraulic trim in our class -- trim pump, cylinder and associated hardware weigh 20-25 lbs. The battery to run trim and electric start is 17 lbs. My motor weighs 120 lbs., and I weigh 175.
I built this boat with 5mm exterior grade plywood, which weighs about 21 lbs per sheet. 5mm okoume marine plywood is probably slightly lighter. Also, I use a high, double-thick coaming, for minimal driver protection. Lower, single layer coamings could be used if you prefer. Some weight savings could also be realized by using 3mm plywood for the deck.
The Pro Vee is likely to be slightly heavier than the Mini Vee. The Pro is longer and the bottom planking is laminated with two layers of 3mm, which is naturally heavier than a single layer of 5mm. Performance is similar for the Pro Vee and Mini Vee. The Mini Vee is simpler to build.
I have not tried very hard to keep the weight down when building my v-bottoms, because I know they will always be plenty light for our classes. Eliminating ballast, trim, and battery from my boat should reduce overall weight to about 575 lbs. Reducing all possible weight during the building process should be good for another 10 lbs. That's getting pretty close to your 551 limit.
ADD: The latest Mini Vee that I built... weighs 140 lbs. That's a true bare hull, with no finish other than the inaccessable spaces under the deck, and no flotation poured yet.
Pro Tunnel Trim
"...do you need trim and tilt and if so what units do you recommend?"
You don't absolutely need trim but it is highly recommended, both to get the most out of your boat and to keep it under control. The Pro Tunnel is going to generate a lot of lift, especially past 50 mph. A little wind gets under the bow and you'll want to be able to trim down in a hurry.
It is relatively simple to make a trim setup using a cylinder and a pump. I provide some information about that HERE.
"Hi, im building a Mini Vee, is there any downfall in using a long shaft? I would just build up the transom and use a jack plate for adjustment correct? If you have any suggestions i would apprecaite it."
A couple of our Mini GT racers use longshaft motors (on Mini Vees) without any apparent problems. In fact, rumour has it there's a little more horsepower in a longshaft, something to do with the longer exhaust housing.
Both of these racer's boats have transoms built for shortshaft motors. One of them has an elongated jackplate -- the adjustable part is made five inches taller than the plans call for. The other guy put a taller motorboard on a regular jackplate, reinforcing the board with some steel angle.
Pro Vee Speed?
"I live in Nova Scotia, Canada. We have just started a small racing association. I am currently running a modified duck hunting boat(my design). Raced an older evinruide now I have a early 90’s 25hp Mercury, 10.25x13 prop, and am getting speeds between 34-36 mph. Using your plans what kind of speeds could I expect (I weigh 185)?"
The Mini Vee will go 40-43 with 2-cylinder 25hp Johnson/Evinrude. I weigh 175 and need to carry 20-25 lbs. ballast to make weight -- 600 lbs. including driver.
I don't know how the Merc compares to the OMC performance-wise.
Mini Vee is simpler to build, and maybe a bit more stable than the Pro Vee. I never ran a Pro Vee with 25hp. Ran 45-47 with 35hp, same as Mini Vee.
Pro Vee in Rough Water
"Are the Pro Vee hulls capable of handling choppy waters?"
The Pro Vee is not particularly suited to rough water. The Mini Vee, with its narrower pad, is somewhat better.
Pro Vee vs. Critchfield
"I am looking at the Pro Vee boat plans. I'm not planning on racing this other than in the river. My brother has a 13 ft Critchfield. How would this boat compare?"
I believe the Pro Vee would compare very well, and in particular would be quite a bit lighter -- maybe by 100 lbs. if the examples I've known are typical. Barehull weight for either of my v-bottoms will be 180 lbs. or less.
The Mini Vee is also a good-performing boat, and will do quite well against the Critchfield.
Mini Vee vs. Super Spartan
"I am considering building a Mini Vee. This will be my first boat built and I am looking forward to getting started. My other option would be a Glen-L Super Spartan. If you could help me decide I would be very thankful. I am not going to be doing organized racing but I do want my boat to be fast and agile. I want it to do at least forty mph"
For flat-out speed you will likely do better with the Spartan. But hydroplanes are not known to be agile. You can see them in races taking very wide turns, while v-bottoms will turn quite tightly, only out-turned by the tunnelboats.
The Mini Vee runs 40-42 mph with a 25hp OMC (Mini GT class), and 45-47 mph with a 30-35hp OMC (GT Pro class). Both of these classes are subject to minimum weights, so your rig will likely be lighter (I'm about 175 lbs. and need 50 lbs. ballast to make weight) and therefore a bit faster, and certainly quicker.
In a hydro you will be driving on your knees. In the Mini Vee you'll be comfortably settled in a seat (plans available) controling your throttle with your foot. Oh, you can put a seat in a hydro, but they are really meant to be controlled, partially, by the shifting weight of the driver.