Keel Shape Reccommendations and Michlet Help

Hello all! Recently I've been getting into boat design and attempting to learn the softwares. Currently, I'm attempting to create a canoe that balances its straightline speed and its maneuverability. The canoe currently has a teardrop shape with a shallow arch keel that becomes shallower towards the aft, and steeper towards the bow. I was wondering If anyone could take a look at the model I have and give any recomendations?

Also, I only have access to the free version of Delftship. As far as I know, it can only really test the boat against straightline resistance. I recently downloaded michlet to see if it would be able to test for maneuverability. I don't believe the free version of delftship allows me to export into the in.mtl file that michlet requires. Would anyone be able to use their version of delftship and send the in.mlt file here? Another thing about michlet that I'm confused about is the "godzilla" extension. I'm pretty sure I downloaded this extension (it shows up in my files where the michlet application is), but I have no idea how to use it or even open it.

Last thing, if anyone has any (preferably free) softwares that can test boats for maneuverability, please share them here.

Sorry if this is a lot, I'm just very new to this world and it's very hard to find the assistance online for the specific issues I have since these topics are pretty niche. Thank you all

 

Can you post a pdf?

 

I don't think so, these are the only options I have for saving the model. Unless you mean a text file
>

 

I think gonzo would like to see your lines plan printed to a .pdf and then posted for viewing.

 

Ohh okay. Thank you

 

Here it is

 

Michlet is very good at predicting drag in slim hull shapes, there are a multitude of variables to consider, all interrelated. Not an easy task. I'm not sure about maneuverability and how you would quantify it.
Godzilla is an optimization module in Michlet that seeks to find an optimum solution for a specified condition. I use it to find a shape best suited for specific conditions for marathon racing canoes.
Your prototype canoe looks reasonable but in my experience that much asymmetry will not be optimum and the relatively flat keel line will definitely not be maneuverable.
Best wishes on your journey, I've dabbled in small boat design for a long time now and it's been an interesting trip.
Ask specific questions and I'll be glad to answer though some may be like "maneuverability" ; I don't know but here are the rule of thumbs ;-)

 

Oh, that’s interesting. A lot of the research I’ve done says that a flatter, or shallow arch, bottom allows for better turning ability, but sacrifices straight line speed. I think the idea behind that is that the flatter bottom experiences less drag since it doesn’t “stick” down into the water as much as a V shaped keel, and would instead kind of “skid” over the water during turns.

The competition that I am designing this canoe for requires the boat be made out of a pretty heavy material, and it will experience pretty heavy loading scenarios. The race that will have the worst loading scenario has 4 paddlers in the canoe, bringing the estimated total weight of the boat to about 1,000lbs. Would this heavy nature of the canoe cause it to experience different rules of thumb than the ones you’re mentioning?

I went with this design because a lot of the other teams who place high have similar asymmetric “teardrop” hull shapes and flatter or rounded keels.

 

Colton,

Welcome to the Forum.

So, this is a one-off, race specific build?
We'll need the race rules and regulations, course description,
likely race conditions ( sea state on race day ), and any other details
you may have.

Why are the build materials heavy?

I have built, raced, and won competitions like this.
I'll see if I can find the video.

Most importantly are the rules.

 

The competition requires the canoe be made out of “lightweight” concrete. And yea it’s pretty race specific. We are required to build a new canoe each year. Here’s the rules. It contains everything you’re asking for, including the courses. Basically there are two slalom races (male/female) and three sprint races (male/female/co-ed). The body of water is, more often than not, a small to medium sized inland lake. The most prevalent external forces would be wind and recreational motor boats, though it’s a little less often the motor boats be too close.

 

Okay, thanks, I'll have a look at the rules.

For what it's worth, here is a video of our race.
Volume down as Jason gets rather excited.
You can see a stern view at the 1:00 minute mark.
And again at 2:04
Then skip to 5:00 for some other views of the hull design including in profile around 5:45
Front view starting at 9:35
A good hydrofoil flexibility shot at 9:54

 

Holy poop, that's a long rules statement!

I think studying those that have competed before you would be valuable.
Search on this Forum as well for past threads.
Don't get too hung-up on the hull shape, it may be more about a design that reduces the weight.
Weight is the enemy of speed.

EDIT: If you search ASCE in the top right search window, you'll find quite a bit of past threads and info.

 

Number one trick to designing race winning canoes is careful selection of clients. I've designed a number of craft which have helped paddlers win and set records in the Texas Water Safari., MR 340, Yukon Quest, The Phoenix cardboat boat race and others. Note; none of the boats won a race or set a record, they were tools that paddlers used in winning. A slight hint, if you are serious about winning you need to start training now, if boats won races I'd have a trophy for the second New River race in Belize some years ago.

I read (skimmed) though your rules, paid no attention to a lot of it, the chances of me dabbling in high tech concrete canoes at my age is pretty slim ;-).

I did however pick up on the two most important constraints from my perspective (1) No length restriction (2) It's a sprint event with an interesting mix of paddlers and course.

Now excuse me while I get up on my soapbox and ramble a bit.

Bluebell is right, weight is the enemy of both speed and maneuverability. At a certain point you will wring most or all of the excess weight and will be left with arriving at an optimum shape for the designated conditions.

IMO there is no such thing as a "fast" canoe per se. There is close to an optimum shape for a given displacement at a specific speed or range of speeds. Michlet/Godzilla is good at seeking and finding those shapes.
As an example, I have thought for some time now that the rule of thumb that straight keeled craft are faster was because of rule driven length restrictions. Optimization is really finding the least amount of drag for some given condition of displacement/speed.
That drag is the sum of friction drag and wave making drag. At relatively low speeds friction dominates and a relatively short curvilinear shape is best. As speed increases wave making begins to dominate and to make it interesting it's not a linear function by any means.

Finding that sweet spot is what Godzilla is all about. In the past Godzilla would invariably arrive at a surprisingly long hull with a midsection very close to midships and a relatively low prismatic coefficient, with enough rocker that the ends were almost out of the water. Restrict the length and the rocker got progressively smaller down to a straight line keel and the prismatic coefficient went up.. The inference to me was that that the shorter boat was pretty much like the longer boat with the ends cut off.

Take this with a grain of salt, after years of believing a catamaran was never the solution for speed since you start out with a 41%+/- penalty in added wetted surface I was asked to consider some alternatives for a craft to tackle the 24 hour distance record. Turns out Godzilla arrived at a long skinny catamaran for the given conditions.

Postscript; I just remembered that I was asked for some thoughts on the concrete canoe race many years ago but I can't remember the details at the moment.

 

Is the teardrop with the wide part at the bow? That was an old theory from many centuries ago that has been proven wrong. Look at fast canoes or row boats, and study their shapes. To start with, what speeds are you expecting to achieve? That is one the critical values that will drive the design.

 

The teardrop just refers to how the canoe looks from the top-down view. The wide part is the stern and the narrow part is the bow