any naval archetects on board?

[oops!]

i lucked out and found two very experienced, glass men. capeable of full hull fabrication and alteration.
one is a west coast salty dawg thats done many extentions, the other is a glassman that fabricates the hulls (plugs to gell)
as a project, we wanna extend and add a "step" to the hull of an older boat.

what we gotta know is where to step it, what are the factors? were thinking a 3 inch step four feet foward of the transom. (thig is a "gee i think we should do it there" kinda estamate)

and the other thing is.....
after the step....where does the outdrives anti cave plate go????
(how high or low do we mount it?)
would it be three inches lower than the bottom of the hull? or hull hight?

any expert assistance would be appreaceated..
all of our n/a's in the area are on mexican holidays!
the project starts jan 3 ! with compleation in early april (in a perfect world)

thanks
oops

 

[oops!]

Re: any naval archetects on board?

sorry
more info....
v hull
19 foot overall.
16.5 feet at the waterline
transom with at the waterline 62 1/2 ins

1 foot from the existing waterline to bottom of hull at transom

any thing else u need??????

 

[tashasdaddy]

Re: any naval archetects on board?

pictures!!

 

[ondarvr]

Re: any naval archetects on board?

What made you decide to do this?

Steps are tricky, it may take a great deal of experimenting to get it right and they don't always help, especially if the hull wasn't designed with one in mind.

I travel to Kelowna a great deal, who are you working with on this?

 

[ondarvr]

Re: any naval archetects on board?

You said you're going to extend the hull, does that mean adding a four foot step section, or changing the current hull at the four foot mark and only extend it a small amount.

 

[oops!]

Re: any naval archetects on board?

sorry its taken so long to reply to this. every time i type in a sentance another group of coustomers comes in

19 foot 69 sea ray. srv 190

the hull extension will be done one of two ways. we cut at approx 2 feet forward of the transom, the reason for this is, thats the flattest part of the hull. the step would be in the fabricated extension area. approx four feet from the transom. the extension is approx three or four feet. this method would give us two joints in the hull. but the step would be one solid peice.

the other way discussed would be to just cut off the transom. put the step at the joint and run the extension from there. this would just give one joint. but the joint would be at a critical stress point. four feet would but the motor behind the step. and while plaining the whole weight of the boat would be on the step

i am also increasing the total amount of bow to stern stringers from 3 to 5.


what made us think of this?? lack of fear and common sence
i am compleatly re doing the interior and need more space.
as long as im extending the hull, i may as well add a performance step while im there.

the glass guru that is going to be doing the fabricating. is the guy that built the plugs and moulds and hulls for safara. (a high end wakeboard boat. hundred grand type high end) he is currently here doing more fab work for them. this guy really knows his stuff, but he builds from plans. not scratch.

TD picks??? this is oops yer talkin to (lol) the last ones i posted came out so huge spinner and dj had to run out and buy bigger monitors!!!

ill practice and get them on asap!

thanks
oops

 

[oops!]

Re: any naval archetects on board?

hope this is the right size

 

[oops!]

Re: any naval archetects on board?

ill be rebuilding the cradel tommorow. but thats the best pick i have from the side rite now. were thinking of cutting about where the last 2x4 is on the vertical. and adding the stepped section (approx 4 feet) there, problem is all the info ive read on steps, there doesnt seem to be a formula. on multi step hulls they just say one approx midships and one approx 3/4 hull.
and there is literally no info ive seen on the height of the anit cav plate.
if the step creates the air cushion under the hull a cave plate at regular height would be in the wash of the hull.
but if the cav plate is too low the drag would increase thus eliminating the advantage of the step.

any books that you know of on this subject?

thanks
oops

 

[ondarvr]

Re: any naval archetects on board?

I work with Svfara, I was just there a couple of weeks ago dropping off some gel coat.

I was interested in stepped hulls a long time ago and did a good amount of reading about them and my customers were looking into them also, but I can't remember many of the details now.

There's a few things to look into. How fast do you plan on going, they don't do much at lower speeds so you need HP. They can also affect the handling (turning), at speed it can get sloppy.

The seems or joints won't make a difference, with the correct layup they will be more than strong enough, so it won't make a big difference whether there's one or two.

For design suggestion, or to see if it's even worth trying you, should check with the guys at Scream and fly . com They like to do all kinds of crazy go fast stuff.

 

[oops!]

Re: any naval archetects on board?

thanks rvr
you work with safara? fizel is gonna help....if i can afford him. really cool guy. only talked for bout an hour but was really impressed.

im gonna jump over to that site and have a look.

only looking to do 60. but if i go 383 stroker with mods to get rpm. my mechs say i might get as high as 70 with a 29inch. not that im shooting for seventy, if it happens thats great. the boat will be approx 2600 lbs loaded. thats a guess at this point.
i dont intend on turning a great deal at that speed, my cruising is only around 25 mph so i dont think "loosing it" in a corner will be a factor.
the boat has an inverse chine toward the aft so rite now it bites pretty good.
what speed do you think the step will give an advantage? (if it does)
are u commin up here sometime soon?
sounds like a good excuse for a corona!

cheers
oops

 

[ondarvr]

Re: any naval archetects on board?

I'll be in Kelowna the week of Jan 21, I'll be going to Armstrong and Winfield on that trip too. I have a lot of customers between Penticton and Sicamous.

 

[oops!]

Re: any naval archetects on board?

sounds like a good excuse for a corona!
the boats not far from the back road to winfeild.
gee mabe youll have time for a rockets game with me and my girl.

drive safe on that crazy hi way (the coquhalla)

i was thinking of what u said bout the step.
the boats only gonna be 23 of 24 feet.. how much is really gonna be in the water any how???
is that whole exercize just a waist of time?

 

[oops!]

Re: any naval archetects on board?

heres a better side shot.....if the pic works....

i was on another fourm, the step thing is very complicated. im reading as much as i can but...it doesnt look good rite now.

the calculations to figgure out cg are impossible at this point.
i have no idea what motor ill be using, or what the boat is gonna weigh loaded.
not only that, the fuel tank is in the front, so the cg is not a constant, it will move with passenger load, coolers and the amount o beer im carring!
a step seems good only at one speed. thats why longer boats have multi steps. so the air can get sucked in under two or three stages during accelleration....
unless im missing somthing.....the step idea on this project is looking useless
id really like one for the overall effect of the boat, and if it worked the 5 mph increase.

am i on the right track with this or am i missing somthing simple?

cheers
oops

 

[oops!]

Re: any naval archetects on board?

that pic was supposed to be a lot smaller