Newb here with a question on props

[ToneDef]

Thanks, I'm building it from a set of Glen-L plans. It is a shallow vee up front and not-quite-flat in the rear; there is a very slight radius to it. They call it a monohydroplane.

[capnzee]

Glen L has been around for a good many years! Hope you are ready for the pounding you are going to take from that flat bottom. Are you planning on kneeling or sitting?
Now that you are familiar with this forum you may want to shift down to "SHOW US YOUR BOAT" and post on that thread.
Those Aussie guys have some great pictures and some great ideas for boats similar to the one you are building--check out the V-bottoms and how they ride--check out their props and what they have to say about them, you may want to make a few changes. As I said before, Glen L has been around for years and a lot has changed since he started publishing plans. Rod

[ToneDef]

LOL yes I hear the hulls can be pretty rough even on flat days. I'll be kneeling so hopefully I can use my legs to take some of the shock. I saw some of those mini V boats in the pictures section and all I could think was "where can I find plans for one??"

[Chairman]

LOL yes I hear the hulls can be pretty rough even on flat days. I'll be kneeling so hopefully I can use my legs to take some of the shock. I saw some of those mini V boats in the pictures section and all I could think was "where can I find plans for one??"

May I humbly suggest you take a look at my site? www.dillon-racing.com

[ToneDef]

Well I believe I have found my next build! It appears to be 1/2" marine ply?

[capnzee]

I know you are going to hate to hear this, but I believe you can "save" the boat you have started on. It would not take a lot of work to roll the work you have completed so you can work on the bottom, remove the stringers and build a Vee bottom in place of the flat bottom. I'll bet you could get one of the guys like "chairman" to assist you on this. A flat bottom may be a little faster, but in today's water it sure gets rough--adding a Vee to what you have would also make a little deeper boat and you could think about sitting instead of kneeling. Feel free to say "no thanks, I'd rather do it my way!" and I must say it looks like you are doing a great job of building. My dad and I built a boat similar to what you are building way back in the 50's (tells you how old I am). The first one was out of Popular Mechanics, it was called "SKEETER", then we built a second one with non-trip chines (much like the one you are building) What I am trying to say is what you are building is a very old design--I would bet the transom is designed for a 15" mid-section engine and yours is most likely 20 inches.

[ToneDef]

I know you are going to hate to hear this, but I believe you can "save" the boat you have started on. It would not take a lot of work to roll the work you have completed so you can work on the bottom, remove the stringers and build a Vee bottom in place of the flat bottom. I'll bet you could get one of the guys like "chairman" to assist you on this. A flat bottom may be a little faster, but in today's water it sure gets rough--adding a Vee to what you have would also make a little deeper boat and you could think about sitting instead of kneeling. Feel free to say "no thanks, I'd rather do it my way!" and I must say it looks like you are doing a great job of building. My dad and I built a boat similar to what you are building way back in the 50's (tells you how old I am). The first one was out of Popular Mechanics, it was called "SKEETER", then we built a second one with non-trip chines (much like the one you are building) What I am trying to say is what you are building is a very old design--I would bet the transom is designed for a 15" mid-section engine and yours is most likely 20 inches.

I hear where you're coming from, and I do understand that it is an outdated design, but it's just a jumping off point; something to get started in fast boats. It would be a great deal of work to convert it to a V bottom at this stage, those pics are a few weeks old and the bottom is now all planked, and I am willing to bet the wood will tear before the West System bond breaks if I try to remove that planking. I enjoy building boats almost as much as I enjoy using them, so all the better if I find another design that I like to build right?

Even still, I could take the current design I've got, (plans include for a 9'6" model as well as this 8'3") and build that, modifying the transom and frames for a V bottom. It would just pain me too much to rip off all that 1/4" okoume and cut into her!

[JohnsonM50]

Id agree there, tearing it up will be hard on the brain. Id say finish-er up & run. Do you have boat experience? The other race skills will no doubt be in your corner but with boats go fast tech is harder to come by. Keep in mind wheels coast, water wont allow for much & is far more resistant than air. That & your going without the 5 or 6 gears of a bike. Pretty much a gear ratio & a props pitch against the resistance. Simpler machinery = more complicated to make go. Best advise is run it with what you have. Over pitching the prop will kill performances get up & go. When you get real rpms & speed to make an educated guess with then invest in a prop. Ive gotten good props on ebay in the $100 range, even less [thanks Ron] At the point where you seriously work to speed it up youll need to do it methodically. Every prop will have a different sweet spot on height & or angle. Take notes & dont make too many changes at once, you want to know what works to apply to your next move.
I started into this with a build too & learned my way along, one thing for sure is things often seem like they should be what they arent. 50mph is a tall order.. but not a pipe dream. The stock motor/prop set deep enuff to work yet hi as can be will probably get ya to the mid+ 30s. Good Luck

[ToneDef]

Id agree there, tearing it up will be hard on the brain. Id say finish-er up & run. Do you have boat experience? The other race skills will no doubt be in your corner but with boats go fast tech is harder to come by. Keep in mind wheels coast, water wont allow for much & is far more resistant than air. That & your going without the 5 or 6 gears of a bike. Pretty much a gear ratio & a props pitch against the resistance. Simpler machinery = more complicated to make go. Best advise is run it with what you have. Over pitching the prop will kill performances get up & go. When you get real rpms & speed to make an educated guess with then invest in a prop. Ive gotten good props on ebay in the $100 range, even less [thanks Ron] At the point where you seriously work to speed it up youll need to do it methodically. Every prop will have a different sweet spot on height & or angle. Take notes & dont make too many changes at once, you want to know what works to apply to your next move.
I started into this with a build too & learned my way along, one thing for sure is things often seem like they should be what they arent. 50mph is a tall order.. but not a pipe dream. The stock motor/prop set deep enuff to work yet hi as can be will probably get ya to the mid+ 30s. Good Luck

Thanks JohnsonM50, I've got a 1957 Whirlwind 16' runabout with a Johnson 60 Sea Horse as well that's currently in the water, she runs 40-45 MPH, but we've got the engine de-tuned a bit for longevity reasons. Also I forgot to add the engine is a 18" leg, and I've got a jackplate with 6+" of adjustment

[Chairman]

Well I believe I have found my next build! It appears to be 1/2" marine ply?

Plywood thickness depends on the design. I've built tunnel boats with mostly 6mm (1/4") and a 3mm deck. My last tunnel had 3, 4, 5 and 6mm, trying to keep the weight to a minimum. My Mini Vee works just fine with all 5mm or 6mm. But my Pro Vee has a curvy bottom that is built up with two layers of 3mm.

The Mini Vee is really a fairly simple boat to build and a nice performer. Will go 40-42 with a 25hp OMC and aluminum prop (Mini GT class). Will go 46-47 with 35hp OMC (GT Pro class) and a Yamaha-style cleaver (courtesy of Ron).

I just bought a "real" cleaver from Ron, hope to be able to test that in a week or so. We're hoping to push GT Pro to 50 mph.