Bracket tub shape opinions
 

Still gathering materials but meanwhile devising a plan for the mold. After looking over all the pics I could find, I decided I want to try for maximum flotation and looks.

So I enlisted some help from the capt and traced the hull bottom then cut it out so I could have a visual aid...

Some help from the capt....

http://i94.photobucket.com/albums/l1...capts-help.jpg

Getting the bottom traced
http://i94.photobucket.com/albums/l1...ll-tracing.jpg


And here's the shape so far..the inside of the blue tape....it follows the 21 degree panel and blends over into the 13 degree panel. Maximum width is 52 inches. The flat section of the tub's keel is 3.5 inches above the flat section on the hull's keel to leave room for a garboard drain. I think I left enough room on the sides for tabs....and I can also put a little slope on the sides. I should be able to mount the motors on 30 inch centers.....a couple of inches wider than stock....and which right now is looking like it will be twin 140 zukes.
The mold building will be a little tricky but I think I have a plan to keep the front and back parallel and at 13 degrees while I get the sides and bottom fixed in place. I'll know if it works in the next couple of weeks as I try to build it. It should have a lot of flotation. I'm still considering the setback....I'd like to keep it as short as possible and still be able to trim the motors all the way up. I'm not sure the distance from the inside of the transom to the end of the cowling on those motors....if somebody knows please chime in.

http://i94.photobucket.com/albums/l1...ub-outline.jpg

Re: Bracket tub shape opinions
 

Nice Captain! :)

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1bayouboy Glad to see some Class pix's. :D

Call Brownspoint Marine and have them send you the PDF "Setup File".
http://www.brownspoint.com/index.htm

The imfo is not in the factory manual.

Re: Bracket tub shape opinions
 

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Re: Bracket tub shape opinions
 

Looks like you are on the right track. I think you are looking at a 26-27 inch set back for Zuke 140's. Bigshrimpin knows...we designed his for a single 140 Zuke. Maybe he will chime in. Were will the anticavitation plate on the motors sit in relation to the bottom of the bracket's transom.

strick

Re: Bracket tub shape opinions
 

Seems like it should be about even with the bottom of the tub as long as it's no more than an inch above the boat's bottom per foot of setback. The bottom of the tub at the engine mount centerlines is two inches above the bottom of the middle bottom panel. If I use a 30" inch spacing on centers it puts the motors just about even with the first chine. Not sure if that's good, bad or indifferent.

Re: Bracket tub shape opinions
 

The motor's will be much higher than that.

Re: Bracket tub shape opinions
 

Thanks guys....that's exactly the kind of discussion I wanted before I start sawing MDF....

Here's some outlines....My question is should the anticavitation plate be above the bottom of the bracket. I know on the brackets that angle up you can mount the motors higher and not hide the prop behind the bracket, but on a bracket that follow the line as the boat's keel all the way back it seems like I shouldn't get the anticavitation plate above the bottom of the bracket....just like on the boats transom. I can get the motors higher by moving them out from the center somwhat which I'm doing. So the red line is the motor and cav anticav plate; the orange line is the bracket's transom, blue lines show spacing in inches....I threw it together and it's not square....when I draw the pattern on a drawing board it will be..... :rolleyes:


http://i94.photobucket.com/albums/l1...om-outline.jpg

Re: Bracket tub shape opinions
 

Ideally you want it were the red lines are. The anticavitation plate on my suxuki is right at the bottom of the keel of the bracket....just like if you had it mounted to the transomon the boat. Mount the bracket so you have the anticavitation plate 1 inch up for every foot of set back. Thats the starting point. You may have to raise the engine even more so I would make sure that once you mount the engine you have room to move it up or down and still have the anticavitation close to were the red lines are. But what the hell do I know I'm just a veterinarian. Maybe someone who knows what they are doing could chime in. :D Gotta get to work.

strick

Re: Bracket tub shape opinions
 

This poses some interesting point's as the tub on a Seamark is different.

Here is the file from D&D that I used. Don has now put it on his website, so I will show it. I kept this file offline in the past.

http://www.dadmarine.com/doc.htm

He told me after I mounted my bracket that the bottom should be 3in up from the keel. :D

But that doesn't jive with the rest of the install imfo.

On my boat [different from your SeaCraft's] My motor's are raised to use the bottom motor mount hole [or will be] they are in the next to the bottom hole right now and the anti cavitation plate is still below the water surface by aprox 3/4in when on plane.

The tub size is lacking for 2- DF-140's and I'm thinking of building a bracket now.

http://www.classicmako.com/projects/xshark/bw19.htm

Re: Bracket tub shape opinions
 

I really appreciate the discussion guys.....

The pics of the seamark look like the tub's bottom is straight back from the transom, parallel with the boat's keel. Not sure the distance up from the bottom. The outline I have is 3 1/2 inches up from the bottom on the center 21 degree deadrise panels, but only 1 1/2 inches above the middle 13 degree panels. I can vary it in any way, but I wanted the max flotation I could fit. I thought the effect should be similar to a stepped bottom.....but what do I know....it's my first attempt.

I could run the 21 degree deadrise portion farther up before the transition to 13 degrees. I avoid trying to slope the tubs bottom upwards as it goes back just because that seems harder to lay out in a way to build a mold.

Re: Bracket tub shape opinions
 

Looking at the D&D page, it looks like the top of the bracket where the motors mount is supposed to be 28 1/2 inches above the boats bottom in line with the motors. That's moving the motors up 3 - 3 1/2 inches....but I thinki t assumes the anticavitation plates will be below the bottom of the bracket.

Re: Bracket tub shape opinions
 

That is correct from what I see too, thus it has more flotation.

The flotation can be deceiving for us average Joe. it's not until this stuff is all mounted and floated until you get a better understanding.

Let's look at the side of the tub alone. Where will the waterline be?

Upon first looking at it will it be 3in, 4in or 5in from the underside of the platform?

The point here is, that anything above the waterline just add's weight and has no effect on flotation to help the boat sit level.
Only what is submerged does have a effect. So we want more area that will be submerged to help the boat sit level.

That means a wider and deeper tub. It also means more volume going aft of the transom.

From this:

http://www.classicmako.com/projects/...s/bracket7.jpg

To this:

http://www.hermco.net/images/wophog/wop0094.jpg

Re: Bracket tub shape opinions
 

And it looks like if that motor was trimmed all the way down, the anticav plate would be just about at the keel of the bracket....

Nice that the bracket has a prop pocket for the trolling motor...

Re: Bracket tub shape opinions
 

Give me a shout if you need another set of hands,as long as one of them has a cold one in it of course!

Here are some pics of your junk from Bobby G's Place, thought you might want them.
http://img.photobucket.com/albums/v3...r/IMG_0174.jpg
http://img.photobucket.com/albums/v3...r/IMG_0173.jpg
http://img.photobucket.com/albums/v3...r/IMG_0172.jpg
You may need to change her name to "Playmate" after the stack of 1978 Playboys that came out of her!

Donnie

Re: Bracket tub shape opinions
 

You're on there SC.......I think the beer to epoxy ratio is 1/1...;)

Some quick calc's....with a 28 inch setback and a width of 52 inches that'll be 1456 square inches...or 10.1 square feet. So for every inch above the sloped bottom it sinks in the water, that's 0.84 cubic feet...which is 50lbs of flotation. The V bottom is about 8 inches down from the corner so that should be equivalent to 4 inches for the area
which would be 200lbs of water. So I should have 400-500 lbs of flotation...... The old water line on the transom was about 18 inches up from the keel which would give me 14 inches or so of bracket in the water. I think I need more beer to think about this any more...

Re: Bracket tub shape opinions
 

Why don't you just go buy the aluminum bracket I have up at Bobby's place and be done with it??
Donnie

Re: Bracket tub shape opinions
 

I like that idea. It might provide a little more flotation. You can make a more dramatic reverse chine in it also if you want. I think the seamark has a bit of a reverse chine in it. Lets keep in mind that the shape of the flotation chamber is as imortant for boyancy as is the size. My bracket down side up.

http://www.casdvm.com/photos/DSCN3836.JPG

I snapped a couple pics of the motor today to see exactly were my anticavitation plate sits. It is actually about 1.5-2 inches below the keel of the bracket.

http://www.casdvm.com/photos/DSCN5621.JPG http://www.casdvm.com/photos/DSCN5622.JPG

Looking back I probably could have made the sides of my flotation chamber deeper thus providing more flotation. Also I probably could have mounted the bracket 1.5 inches lower.

Here are more pics:

http://www.casdvm.com/photos/DSCN4274.JPG

Make sure you leave enough room for your transducer if it is going to be a transom mounted.

http://www.casdvm.com/photos/DSCN4390.JPG

make sure that you can stand on it and have dry feet....

http://www.casdvm.com/photos/DSCN4401.JPG

Why in this photo does it appear that the bracket could be mounted a little lower....

http://www.casdvm.com/photos/DSCN5543.JPG

while in this photo it looks like the bracket is mounted just right....


http://www.casdvm.com/photos/DSCN5554.JPG

Theres a lot for you to consider. It hurts my head to think about it.

strick

Re: Bracket tub shape opinions
 

HeHe You bring up even more question's Chuck. :D

How does the anti cavitation plate look when your on plane?

Is it underwater or even with the surface. Do you get a bunch of spray off of it?

In the last 2 pix's. from what you stated look's backwards to me. I realize the boat is in gear in the bottom pix.

It's hard to see in this pix, due to the Black color. I have aprox 4in between the water surface and the bottom side of the 2in band around the swim platform when the boat sit's at rest.

http://www.classicmako.com/projects/...terpixs004.jpg


Now let's forget the bottom of the bracket for a sec.
With a stright edge extended out from the keel of the boat. Measure from the top side of that stright edge to the anti cavitation plate. What that figure?

Re: Bracket tub shape opinions
 

Hey SC....where's the fun in that... :) but really...what kind of bracket have you got??

Good pics Chuck...that bracket looks great....and good questions. and thoughts. I was going witha thru hull but leaving a little room might be a benefit later. I think the wide tub is going to have enough flotation.

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I honestly don't know the specifics on it.
You will have to call Bobby.
He had it made for me and it wasn't as wide as the Armstrong so I had Mike at Wildfire order me a wide body.
May be worth a look.
Donnie

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I'm about 4.5 inches up from the keel. There is minimal spray coming from the anticav plate.I will check to see were the anticav plate sits in relation to the surface while running next time out.

http://www.casdvm.com/photos/DSCN5627.JPG
http://www.casdvm.com/photos/DSCN5625.JPG

strick

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10-4 :D

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HEY WART IF YOU TAKE YOUR BRACKET OFF YOU GONNA SELL IT ?
RUSTY

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Yes.

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I like the "no wrench" drain plug!!

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I use a wrench anyway...I'm paranoid about that kind of stuff :D

strick

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I understand that!! Not to derail the thread but, how is the hole sealed at the garboard drain....for those that have replaced their own transoms?? Any pics of the install/repair??

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What I do is drill a hole to the right size first. Then I use epoxy to seal around the inside of the hole. Then one of these guys gets 5200 in place. I usually have to cut them to the right length then tap them in from the inside the boat so the drain plug fits into it as shown. The drain plug usually gets 5200 as well. Thats just how I do it.

http://www.casdvm.com/photos/DSCN3916.JPG

strick

Re: Bracket tub shape opinions
 

That looks as right as it gets!! Nice job!