# 14' Starcraft Modifications



## WTL (Apr 15, 2008)

I am in the process of totally modding my starcraft into a bass boat that meets my needs. I love this forum, have been lurkin for a while and recently I ran into a safety related issue that I wanted to bounce off you people. 

I removed the bench seats first thing cause I wanted it to be more open. I want to be clear that adding them back is not an option. I have a 28 horse Johnson pushing this. 


Theres ribbing all along, but no stringers as I understand it. When I took it to the lake today, it porpoised and there was a funny feeling in the little console when it did it. I hope I wasn't feeling the hull flex. 



I am using the middle deck like a big bench seat, it is lower than the seats originally were but I am reusing the aluminum angles that went with the seats to add strentgh to the side. 

The problem is I took it out the other day and it leaked some along the seams of each side. A little silicone made it better, but I don't want to be looking at a structural failure in the future. 

Do you guys reinforce the boats longitudally, or is the aluminum hull normally strong enough?


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## Jim (Apr 15, 2008)

Welcome to the forum! 

It seems the becnches were there for more support. Did you take the boat out on the water before you removed the benches?


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## WTL (Apr 15, 2008)

Thanks. Glad to be posting here now. 


Only took her out before with the TM on, I didn't have the outboard yet. I'm sure the benches added some support. 

The middle deck is now trying to serve as a bench, so I am less worried about the boat caving in on the sides. And I still need to get the middle deck in there more solid. But I was just sorta freaked out by that bumping feeling the console had (it could have just been loose, but it only moved when it porpoised hard). I started to think about the structure length wise. Didn't know if yall address that when you do mods. I could also in theory be overpowered, and the outboard is on a 5 inch setback jack plate. Can a boat like this really break in two titanic style, or is that a wives tale?


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## Popeye (Apr 15, 2008)

WTL said:


> Can a boat like this really break in two titanic style, or is that a wives tale?



That's an old wive's tale. A boat like yours will just fold in half front to back like a sandwich trapping you inside while it sinks. :lol:


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## Waterwings (Apr 15, 2008)

flounderhead59 said:


> WTL said:
> 
> 
> > Can a boat like this really break in two titanic style, or is that a wives tale?
> ...



Yes, what Andy said above is possible. 

Fore and aft stringer support in the bottom may help, but there are the still the sides to contend with. You know the throw-away aluminum [tin foil] pans you can get at the grocery store? Ever took one and picked it up by the sides when it had food in it, but the sides were flimsy and still wanted to twist? I believe that's what your boat _may_ be doing (without actually seeing it in person); not positive, but it's highly possible.


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## Popeye (Apr 15, 2008)

Not sure what additional stress is being placed on the hull with a 5" set back jackplate either


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## WTL (Apr 15, 2008)

I think more than anything the jackplate is just screwing up the balance a little, making it stern heavy and prone to porpoising. It seems to have moved the center of gravity back. It only acted funny when it popped up and down. 

OK, so what should I do to be on the safe side. Remember the benches arent going back in, but the floors are serving part of that purpose anyways. Does that 2 part marine foam add enough rigidity or should I look at running a length or 2 of angle up the lenght of the boat (and I suppose attatch more angle supports to the floor up the sides)?


What do yall normally do? I know for a fact I'm not the only one here who has removed bench seats.


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## Waterwings (Apr 15, 2008)

WTL,

Hope you don't think we're being too critical, but we're actually concerned about the well being of you, any passengers, and your rig.


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## WTL (Apr 15, 2008)

Waterwings, 
not at all, I'm not touchy feely. I just want to be on the safe side too. This thing is going out on lake kissimmee with all its swells at some point, it can make the river fine I'm sure...but its gonna be taking a beating and I want it solid.

Back to the jack plate thing, the way its planing is a little off. Like the stern is just a little deep to be said to be planing, but this is at 15 mph or so and its roughly balanced on top of the water, just not like other boats I've been in.


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## Popeye (Apr 15, 2008)

A jack plate will make your stern sit lower. There is "another" site that actually promotes the use of a basketball, jammed in the jack plate and inflated to compensate for it. I refuse to mention that site here but we know who it is. coughBBCcough


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## Waterwings (Apr 15, 2008)

I'm certainly not an expert concerning jackplates, but that could be one of the problems causing the porpoising. Do you have electric trim on the motor, and able to adjust it (in/out)? If so, try trimming it in or out some and see if that helps. The Tracker I used to have would porpoise (at higher speed) if I didn't have the motor trimmed properly. As far as the foam, I don't believe it would add any _real_ structural rigidity to the hull. There will be some more members adding some thoughts to this as soon as they see the post.


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## WTL (Apr 15, 2008)

I missed the basketball thing. Say what now?

Its a homeade jackplate, completely manual. I think I might fiddle with the tilt, its in the 2nd hole right now, might move it the first although I've never seen an outboard run right in the first. Could also trim it up just a hair, its a longshaft motor on a 15" transom hence the jack plate and modded transom.


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## Popeye (Apr 16, 2008)

Oh, some of those guys that have more money than common sense (or deep pocket sponsors) buy those $45,000.00 bass boats with the 300hp motors put on big 'ol 10" jack plates and complain the boat sits low in the back end. One of the "fix-alls" is a basketball shoved in the jack plate opening. Supposedly the buoyancy of the basketball compensates for the motor being set back that far. Personally I think it might help some... however the entire basketball would have to be under the water line AND I don't think just one basketball has enough buoyancy to do the job.


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## Waterwings (Apr 16, 2008)

> ...however the entire basketball would have to be under the water line AND I don't think just one basketball has enough buoyancy to do the job.



Concur on that!


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## WTL (Apr 16, 2008)

I just don't see how that would make a difference if you are on the plane, the b ball should be out of the water. 

I'm going to adjust it some today and tommorow and see if we can't strike the right balance.


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## Popeye (Apr 16, 2008)

The basketball thing is only designed for when you are coming off plane or are stopped. You are correct, on plane the b-ball will be out of the water


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## bluegillfisher (Apr 18, 2008)

The guy that does the book on modifying a jon boat to bass boat says that by putting paneling down the sides of the boat on the ribs you add the support that the benches gave the boat. I guess it would be like building a torsion box. He says to use as long of plywood for the panels as you can get(mostly 8') and screw(or pop rivet) that to the ribs. He also says to put the foam from the benches under the side panels so you don't lose flotation. 
Good luck,
Mary


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## Jim (Apr 18, 2008)

bluegillfisher said:


> The guy that does the book on modifying a jon boat to bass boat says that by putting paneling down the sides of the boat on the ribs you add the support that the benches gave the boat. I guess it would be like building a torsion box. He says to use as long of plywood for the panels as you can get(mostly 8') and screw(or pop rivet) that to the ribs. He also says to put the foam from the benches under the side panels so you don't lose flotation.
> Good luck,
> Mary




That does make perfect sense!


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## GatorTom (Apr 18, 2008)

Your boat is almost exactly like my 16' Starcraft. The benches provide a lot of the structural support to keep the sides from flexing. Without them, your sides are trying to flex out on the sides and fold your bow back to your transom. You definitely need to add some structural support to the sides to keep it from flexing. You can either do like mentioned in the earlier post and use plywood on the sides or you can run several pieces of aluminum angle down the sides to sturdy it up.


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## WTL (Apr 19, 2008)

Thanks for the help talking this problem out with me. This is the direction I am going in right now. I went the other day with another fellow in the boat and the flexing issue or nonissue didn't show up, no leaks on the seams, no funny feeling and no porpoising cause he was in the front. It appears I am on my way to getting it more solid as a craft.

The stern heavy issue still exists, and when I'm not watching the suns-spurs I'm outside working on the jackplate. I'm first trimming it up and taking out 2/3" of the setback by using less of a motorboard, we'll see if that helps some. Its a longshaft motor that was still a little too deep. After I go out again, perhaps tommorow afternoon, I will post how it planes and we will see what tweaks should be done. 

I will also post a full pictorial when I get done with _this _boat.


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## Jim (Apr 20, 2008)

Good job so far!


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## WTL (Apr 20, 2008)

Thanks, but I might not be doing such a great job. Went again today and the problem is back, I guess it just didn't porpoise enough with another man riding in the front the other day. 

It is as if the console is moving 1/2" in my hands when it porpoises at speed, talking 20-25 mph on plane. It doesnt do it when I hit a wake or am going slow. It doesnt do it half way either, when the console bumps its obvious, feels like someone is talking a crow bar and physically moving the thing even though its attatched solid enough to not move when I apply force to it. 

It is attatched almost directly to a rib on the floor using great stuff foam sealant, so the next thing to try is going to be getting a better way to attatch it. I'm seriously thinking of running two angle iron strips up the first 8' or so of the boat and riveting them in, then attatching the console to those. 

I took pictures for you to see exaclty what I'm talking about. I also considered the possibility that somehow the steering cable is pulling the how setup back when the engine torques, but that transom is feeling pretty rock solid and even though the steering cable is tight, I can't recreate the feeling of the console moving. 

BTW, I trimmed her up today to where the cavitation plate was level with the hull and hit 26 mph one time. Its ok if it is glass, but any ripple at all and the bow starts popping up.


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## Captain Ahab (Apr 21, 2008)

WOW - that sounds like the hull is flexing - a lot. You may need to run cross bracing so that you are using multiple ribs to hold the console in place. 

I suggest that you carefully inspect everything - a 1/2" of movement has to leave a wear mark or stress mark somewhere, find it!

Keep us up to date with your progress.


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## WTL (Apr 21, 2008)

One thing that would amplify the flexing is that the middle deck is touching the front of the console, which means if you have the front of the boat flexing, that deck is moving in a different way than the console which is anchored to the floor and it is pushing the console, possibly...just an early morning, sleep deprived idea....


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## Jim (Apr 21, 2008)

This might sound crazy.

Especially coming from someone with ZERO experience (If I try to fix anything....ANYTHING, I break it). What about removing the console maybe, adding a floor underneath it and then putting the console on top of it?


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## Captain Ahab (Apr 21, 2008)

Jim said:


> This might sound crazy.
> 
> Especially coming from someone with ZERO experience (If I try to fix anything....ANYTHING, I break it). What about removing the console maybe, adding a floor underneath it and then putting the console on top of it?



That is what I meant by bracing it - putting a floor type structure under t


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## WTL (Apr 21, 2008)

Jim - you are right if I am just trying to avoid feeling the console move, I think I could solve that problem. 

The only thing is, I am thinking there is the possibility that this console bending like it has has been a blessing in disguise, IE it has made a structural problem very obvious that I need to fix. A floor would probably dampen any feeling of the console moving, but if it doesnt correct the structural problem then I am still at ground zero. 

Of course there is a possibility that what is being amplified here is harmless and present in any boat....the question is where is one overreacting, and where is something a problem. I think if anyone else drove the boat though, they would be scared when it happens too. 

I am going to have to look extra hard for stress marks when I start disassembling, but it didnt leak yesterday.

Here is a paint file of what I think I am going to do, with iron angles going up the middle...attach the console to the iron angles which are riveted into the top of the ribs...


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## GatorTom (Apr 21, 2008)

You need to brace the floor and side running bow to stern to keep it from flexing. The benches were holding it together and preventing the flexing (along with the ribs) before. Now without support in the same areas as the bench, you can really feel it (especially with the console attached to the floor). Your drawing looks good. I would consider running a piece down each side as well. I wouldn't run the boat any more until you get it all braced. Each time you take it out and it flexes, it is potentially loosening rivets and seems that can cause major leaks.


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## Popeye (Apr 21, 2008)

Have you seen the movie Up Periscope or Down Periscope (whichever, the one with Kelsey Grammer)? Remember the scene where the old engineer had a string from side to side to see how much the hull shrunk? Tape a piece of string side to side on the top of your gunnel and see how much flexing in and out the hull does when it porpoises. If you eliminate that, you should eliminate the porpoising.


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## F_I_Sherman NY (Apr 21, 2008)

Is it at all possible that your boat could be overloaded? I have read on other boards that the results of being too heavy cause alot of handling/safety issues and the porpoising etc. you describe are the same indicators. Maybe the flex is a big factor on top of that?


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## GatorTom (Apr 21, 2008)

flounderhead59 said:


> Have you seen the movie Up Periscope or Down Periscope (whichever, the one with Kelsey Grammer)? Remember the scene where the old engineer had a string from side to side to see how much the hull shrunk? Tape a piece of string side to side on the top of your gunnel and see how much flexing in and out the hull does when it porpoises. If you eliminate that, you should eliminate the porpoising.




Awesome idea!


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## WTL (Apr 24, 2008)

Thanks, I'm going to try using the string just to get a take on how much the sides are flexing before I try and fix this.

I went today and saw the flexing for sure in the floor right in front of the console where it is attatched. Didn't see any flexing in the sides. I have to get this fixed, theres no doubt about it will fatigue that metal and one day it will break with as much as its flexing. Now I know exactly where to position the angle too. I'm taking it out one more time before I put the angle in cause I am actually on the road right now and I pass a good lake on the way back, but aside from checkin the string I'm going to idle and just fish.


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## Popeye (Apr 24, 2008)

If you use several pieces of string, side-side in several places and front-back you should get an idea of where you need to strengthen it? Without putting the seats back in there may not be a lot you can do though.


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## WTL (May 7, 2008)

I understand the physics of what is happening a lot better now. 

The sides are bending a little, which enables the bottom to flex. It only happens when it porpoises (as opposed to plowing through a wake or waves) because its bending when the stern is try to lift the bow up. It is not flexing nearly as badly or maybe at all when the pressure is exerted from the bow hitting resistance (such as coming down and hitting the water). 

I have trimmed in the motor more and it did nothing to correct the porpoising. When my freind goes, it cannot be made to porpoise. The porpoising is directly related to weight distribution because the bracket has set that motor so far back. 

The solution for this is to put as much ballast in the front as possible. I am going to try to move the deep cycle battery up a few more feet, and even the starter battery. 

Here is a question, is there a limit to the length of wires I use for the starter battery? I know they draw a lot, so what gauge am I looking at and how far is too far to try and move it (right now the battery is 5 feet from the starter).


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## GatorTom (May 9, 2008)

At least 6 guage.


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## ky_madman (May 13, 2008)

*I have two of those side braces that I took off during my V-Hull build. If you need them, I will send them to you.* Take some pieces of aluminum angle iron, bolt to the sides where the seat mounts were, and then run angle iron across the width of the boat, then brace it to one of the cooresponding rib in the bottom of the boat. Do this front and back as support for your deck and/ or bench. It will eliminate your problem. Sorry but I couldn't see your photos. I'll get photos of my boat to show you what I'm talking about. If anyone can repost WTL's pics, please do.


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## ky_madman (May 13, 2008)

here's some pics





Inside of brace and cross beam




Cross Bracing




Incidently, I measured the open space between the decks, in the middle of the boat and it is 4.5 ft.
From back to front - I used the 1st, 3rd, & 4th benches and eliminated the 2nd. So the distance between the 1st & 3rd seat is ~4 1/2 feet. Hope this helps.


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## WTL (May 27, 2008)

First off I would like to again thank everyone for their advice in this thread. 

I decided on doing a drastic change - I could add all the ballast in the worldbut it would never compensate for my weight being so far back. So I reordered a new teleflex cable that would allow me to move the console and my seat up 2 1/2 feet. I am going to try it out tommorow and see if that did the trick. Also I have now extended the middle deck all the way back and added back the rear bench, only I made the rear bench seat about 3 1/2 feet wide - its what the drivers seat is on. I have braced this against the walls. And I took a large road sign post and riveted it into the top of each of the ribs to add longitudinal strength. I'm taking her out tomorow, and I'm going to try and use the "down periscope" string trick as well as just seeing how she feels. 

Here is a pic or 2, sorry its dark...

KYMadman, thanks for the offer on the braces. I dont think I need em enough to warrant sending them in the mail, I have been making my own from steel, but thanks again.


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