Few Questions on Hull Construction on Iowa Class

1) Anyone have suggestions on a good angle to install the prop shafts at in an Iowa class??

I have read somewhere that if the angle is too great, that the stern has a tendancy to get drawn low into the water while reversing, though I'm not sure that this is a problem in a hull this large unless the angle is really ridiculous.

Does the angle have any noticible effect on the steering/ turning radius??



2) What is the rule on the penetrable area below the waterline when the hull doesn't extend at least 1 inch below it, or when the hull makes a sharp bend inward before it gets to the 1" point?? In the Photo, the top of the notch at the top of the skeg is 1-1/16" below the waterline. (For reference, the lower crosshair line is the waterline, the one just above it is the top of the boot.) Can I reduce the inpenetrable area to make it easier to skin? Seems like it would be difficult to penetrate there anyhow, unless it's under fire from someone who's already on the bottom[]

I'm trying to build to be compliant with MBG rules.





3) Anyone else notice this?? In the hull lines area of the plans, the skeg is over 2" tall, but on the plan side view it is less than 1-3/4" tall, unless I am missing something. When I did my CAD drawing,, I made it match the side view...... OK,.... Not OK????[?]

I do have 2 sets of different plans, and both pretty much show the same thing.








4) In the above drawings you can see that the prop is quite a distance from the rudder. Everyone says to get them as close as possible to improve manuverability. The MBG rules say they must be installed in the same position as on the real ship. What do I do???

 

Ah, it's rule/format blending. The fast gun guys sometimes allow you to change the paramaters of rudder location and suchlike. If you are going big guns, build it to plan. The Iowa turns well enough as is


Mike

 

1) In a ship as big as the Iowa, you don't need to worry about angle at all. Put those props in parallel to the waterline. The only reasons people angle the propshafts are to a) fit in bigger props, or b) get better alignment to motors. Since your ship is so big, you won't have problems with either of those.

2) I believe the answer you're looking for is the "45 degree rule". I'm not completely sure, as I have not read the MBG rules, but that's what most clubs use. My club, the WWCC, uses the 60 degree rule, but the concept is the same and we've got a wonderful diagram explaining the concept in our rulebook:
http://www.westernwarshipcombat.com/images/stories/WWCC_Rules2008.doc

3) I can think of two explanations for this. First, compare where you're making your measurements on the cross-sections to where you're measuring on the side view. The hull outline of the side view is based off the CENTER of each cross-section, while the skegs are to either side. Since the cross-sections are curved, the distance between the bottom of the rib and the bottom of the skeg is shorter than the height of the skeg itself. To be technically correct, the person who drew the plans SHOULD have added a line to show the top of the skeg, where it actually meets the hull. You can check whether this is the case by measuring to the center of the cross-section in question, rather than where the skeg is. If that is NOT the case, then go ahead and burn an effigy of the artist who drew the plans.

 

The only reason I am worried about the angle is to allow easier assembly to the motors by angling the shafts up at the motor end to get them a little farther away from the bottom of the ship. I figured that would give me a little more flexibility if things got a little tighter than I plan for them to and give me extra clearance to add a gearbox or something if need be. I don't know if this is a good idea or not???

Yes, they are Goff plans. I also have a set from BDE that are nearly identical, except on the BDE plans the scale is way off. I don't think it is the BDE plans being off per say, probably just the printer scale a little askew.... the overall length of the ship is off nearly 5 inches on the BDE plans if I remember right. There were several discrepancies on the Goff plans, mostly the heights and widths of the hull lines did not match the heights and widths on the plan views, but the overall length of the top and side view are pretty much right on When I calculate what they should be based on data from the USS Missouri website:

http://www.ussmissouri.org/discover/the-ship/blueprints


MBG allows for a 5% error on dimensions. Not that anyone wants to be that far off, but at least it's available if something goes wrong.

There's a copy of MBG rules posted here:

http://bob.roeske.us/mbgrules2006.pdf

Froggyfrenchman said should be reasonably current. I’ll look a little deeper at them, I just printed them and put them in a binder so they are now easier for me to browse.

One more question, I originally planned for a 3/8 thick cap rail, and routing a rabbet into the inside perimeter of it to recess the deck to be flush with it at the top, but I have been rethinking and considering going to a 1/4 cap rail and an 1/8 inch thick deck overlapping it to the edge of the hull... thoughts, suggestions anyone???

 

I gotta run to a date... but I thought I'd chime in here... Andy's mbg rules should have the 45 degree rule. I built my iowa to mbg & that's how I did it. But make sure I didn't just mess up.

Prop angle If anything I had problems with the stern popping up out of the water... Not a big problem, just weight load the back. I have mine set at a slight angle (aft pointing down). I did this (as carl suggested) to accommodate oversized (I think 2"?) props & for easier motor placement. Overall, I liked how it turned out... but If I had it to do over again, I would choose smaller props and less angle so I could set the ship down directly on the ground.

 

Thanks Justin, your post reminded me I didn't phrase properly to see if anyone had any input as to if the MBG allowed for the 45 or 60 degree rule. That part of the post was intended to look a little more like this:



There's a copy of MBG rules posted here:

http://bob.roeske.us/mbgrules2006.pdf

Froggyfrenchman said they should be reasonably current. I’ll look a little deeper at them, but I don't see anything about a 45 or 60 degree rule. I just printed them and put them in a binder so they are now easier for me to browse. Anyone have any input on this??

 

Big gun doesn't allow reversing I thought, so angle shouldn't be an issue. At big gun speeds even if reverse was legal, you wouldn't have to worry it

 

Reverse is legal (you can back up if needed, although it makes you a sitting duck); just not 'battle reverse' ie two ships wouldn't in real life 'jockey duel' stern to stern.

45 degree rule: I read through andy's rules, and could not find anything either. I am, however, pretty sure it should be in there.

This is what I would do.

1.) The guys in MBG are cool; they will not be a jerk about it especially for a new member.
2.) Cutting more off later is trivial; when you resheet just take your dremel & take a little more off. Adding more material is, however, quite difficult; as is sheeting on areas with not enough room.. I would rather err on simplicity.

I would build to 45degree rules and if they have a problem with it, during the first resheeting... cut it to compliance.

 

Thanks guys,
I did talk to Mike Deskin today and he said it was not in the current rules, but that the committe would consider a 45 degree rule and was quite confident that it would be voted in.


As far as the conflicting heights on the skeg on the plans, once again it looks like Kotori pretty much nailed it. Due to the curvature of the hull and the side view appearing to be drawn from the hull centerline, not a cross section of where the skeg is at, that accounts for approximately 1/3 of the height error on the skeg. The rest possibly plan error, scaling issues, or just the fact that the lines are a little on the fat side and somewhat difficult to interpret where they all come together.



Does anyone have any input or pics of ways to do the deck??:

Cannonman:
One more question, I originally planned for a 3/8 thick cap rail, and routing a rabbet into the inside perimeter of it to recess the deck to be flush with it at the top, but I have been rethinking and considering going to a 1/4 cap rail and an 1/8 inch thick deck overlapping it to the edge of the hull... thoughts, suggestions anyone???

 

Oh yeah, about the deck. The way I have always done inlaid decks is to build a 1/4" subdeck (that's the big strong part underneath, hence the name SUB deck) and then lay a 1/8" deck on top of that. I tack it down with a few drops of glue, then cut and sand the deck to conform with the outside of the hull. I then pop the deck off (carefully, so as not to tear the wood), and trace a line about 1/4" inside the edge of the deck. I also trace out where to cut off pieces for the extreme bow and stern, steps, braces, and separate hatches. Anything that needs to get cut gets traced. Then I pick my thinnest bandsaw blade, and cut along the lines. The result is your deck, plus an extreme bow and stern, plus two skinny bow-shaped pieces of wood that I call a caprail. I glue the caprails and bow and stern down to the subdeck, and then set the deck itself down. Voila, instant inlaid deck.

That sounds a lot more complex than routing a rabbet on the inside perimeter, but it is actually pretty easy to do in practice. Either way, you definitely want to have an inlaid deck. If you do not, the deck will be susceptible to splintering when hit from by stray shots, and will require much more extensive hold-downs (usually a @#$%load of screws) which makes maintenance and operation that much harder.

 

Thanks Kotori, That pretty much told me exactly what I needed to know. I hadn't thought much about the splintering problem if the edge of the deck were struck. Sure does help to have advice from an experienced skipper

 

So you say, but I am still a young grasshopper myself. The more I learn, the more I learn there is more to learn! (and if you figure out what that means, you're farther along than many people I know)

 

I guess that makes me a sub-grasshopper, so I am just starting to learn that if I really want to learn that it is best to learn from one who has learned more than I have learned!? .... At least I think...
I've just confused myself[B)]

 

All
I am posting in the MBG area (local clubs) a proposal to add the 45 degree angle for hard area to the MBG rules.
Mikey

 

Thanks Mike!!

 

so what did the jury come back with on the best plans for the Iowa[?]

 

Monk, i would use the ones in the other topic, from archer183:

http://ussmissouri.org/discover/the-ship/blueprints

 

Hey Monk, Sorry I didn't reply sooner -- I've got some big time real life interference going on right now, so unfortunately Ship buliding and forum surfing are kind of taking a back seat right now.

Anyhow, on the plans, the ones from Goff aren't bad, but just like any other plans, they aren't perfect. Like I posted earlier, the heights and widths on some of the hull lines needed to be "massaged" a bit to make sure that they met the other views properly, but all in all, they were pretty useable.

I did start working up a set of hull lines from the PDF files posted on the Missouri website, but after I was done doing the Amidships back lines, I compared them to the ones I had generated from the Goff plans, and although they weren't too terribley close to one another, they weren't so far off that I thought it would be worth the effort to try to build the ship from what was available on the Missouri site, so I decided it would be easier for me to keep going with the Goff plans, so far it's working out OK. If a guy had access to a printer that could print the Missouri plans out at the proper scale, they would be more useful.

So, long story short, with plans in hand from BDE, Goff, And the PDFs from the Missouri website, I went with the Goff plans.

If I get a chance later, I'll post a pic. of the progress on my Iowa hull.

Hope this book I wrote helps !![8)]

 

Thats good to know, i have heard that goff is usually really reliable.