Bunch'o question

[opio]

Well I would like to start by saying thanks to the KEP's 21, FF.12 (now a .18), and the JAP I'm a rigger junkie!!! :blink:

I have a few question about different parts of a rigger design that I was hoping to get some help with.

Lets say I'm building a .12......

1. Is there any starting points for how far forward the sponson's should be located in relation to the tub? How about a good starting AOA?

2. I have seen turn fin's on the sponson's, and on spars, is there any reasons for the two different mountings? and is there a relation between turn fin and anything like cg?

3. What a 'baseline' for sponson depth below the tub? Any rules of thumb on this?

4. How bout depth of rear shoes / skies? besides the depth any pro's / con's of shoes vs. ski?

Thanks for any info I can get! I'm having too much fun and I want to try to build up my own.!!

 

[opio]

must be super ninja information h34r: h34r: h34r:

 

[shawdaddy]

Give it a little while. Don't forget what today is.

 

[opio]

Yea i know bro just havin a bit of fun! lol

 

[Tim_Duggan]

1. Is there any starting points for how far forward the sponson's should be located in relation to the tub? How about a good starting AOA?

Almost every rigger I've looked at have the front edge of the front sponsons in front of the front edge of the tub.

2. I have seen turn fin's on the sponson's, and on spars, is there any reasons for the two different mountings? and is there a relation between turn fin and anything like cg?

Basically comes down to the sponson shape and length. if the sponsons don't have a surface that extends back to the CG it needs a spar. Turnfin to CG placement is important for cornering ability. Exact position depends on the type of boat and type of fin. you might have to experiment.

3. What a 'baseline' for sponson depth below the tub? Any rules of thumb on this?

Depends on the size of the boat but too low or too high and you'll have problems! Best to base it on what other boats of comparable size are using successfully.

4. How bout depth of rear shoes / skies? besides the depth any pro's / con's of shoes vs. ski?

The rears ties in with other factors such as tub height, if the tub bottom is parrallel to the top, tub angle etc. NOW Shoes vs Ski's - both have advantages and disadvantages. Drag, lift, ease of launching, prop "masking" etc. Converting one type of boat from one to the other doesn't always work - there are factors at play in the hull design that usually only suit one or the other.

I Hope this gives you some ideas to ponder over.

Tim

 

[opio]

Hey thanks Tim and Tched your in box was full but thanks you too!

 

[Chris Thomas]

If you are building a 12 rigger. Build the JAP that Rod has been "Handing" out. I have seen videos of that thing and the numbers are right. Don't bother with moving anything......If it is not on the prints? look at the three or more threads that have been posted for the JAP and I'm sure you will find the info in there somewhere. Rod has answered all the questions so far. You will not be disapointed.