? Starcraft cc rebuild idea Convert (2) 26 starcraft islanders into (1) 36ft cc

[191Seanymphstriper]

Hello

 

[Boat Biz]

Re: ? Starcraft cc rebuild idea Convert (2) 26 starcraft islanders into (1) 36ft cc

The scantling sizes will not be strong enought to cope with the amount of flexing as the larger surface areas are subjected to the pressure of wind and waves...

Bigger boat = more flex, more weight and higher strenght required for all associated components

 

[Bondo]

Re: ? Starcraft cc rebuild idea Convert (2) 26 starcraft islanders into (1) 36ft cc

Ayuh,... Sounds like the Loonnngggg way to the scrap heap to Me...

 

[eclark53520]

Re: ? Starcraft cc rebuild idea Convert (2) 26 starcraft islanders into (1) 36ft cc

With enough money time and energy, anything can be done.

I suspect it will be cheaper to sell/scrap/etc the two, and buy a larger boat.

 

[191Seanymphstriper]

Re: ? Starcraft cc rebuild idea Convert (2) 26 starcraft islanders into (1) 36ft cc

Yea well The older models are cheap enough and i have all the tools and equipment to do this! So money really won't be a issue I dont think.

 

[191Seanymphstriper]

Re: ? Starcraft cc rebuild idea Convert (2) 26 starcraft islanders into (1) 36ft cc

The scantling sizes will not be strong enought to cope with the amount of flexing as the larger surface areas are subjected to the pressure of wind and waves...

Bigger boat = more flex, more weight and higher strenght required for all associated components

Ok can you share some phissis on the subject? Like caculated reasons etc?

 

[191Seanymphstriper]

Re: ? Starcraft cc rebuild idea Convert (2) 26 starcraft islanders into (1) 36ft cc

Ayuh,... Sounds like the Loonnngggg way to the scrap heap to Me...

O??? Why? Explain? Why do you think that way about the idea?

 

[Comoxsam]

Re: ? Starcraft cc rebuild idea Convert (2) 26 starcraft islanders into (1) 36ft cc

I do aircraft sheet metal work for a living and I like the way your mind works!

However I can tell you that the rivet holes won't line up. As much as I would love for aircraft parts to be like a cookie cutter and all the holes match it never happens like that. Unless all those rivet holes have been drilled by a computerized machine it is almost impossible to get all the holes to line up. Just a tiny bit off on one hole throws everything out. Get yourself two sheets of aluminum and drill the same pattern of 20 or 30 holes in each sheet. Then place one sheet over the other and you'll see what I mean. So to do it you would have to drill more holes in between the ones that are there. You end up with something looking like swiss cheese.

As far as 4 feet worth of splice goes I think that would be adequate. I've repaired aircraft floats before that had the entire bow ripped off. The required length of splice on the keel and chine seems ridiculously small however that is all it calls for. Floats are closed off on the top though not like a boat where it is open. I would think a 36 ft gunwale would need more support somewhere too. Some kind of bulkhead or something. A 36 ft boat is pretty big and next thing you'll be loading full of people and weight. You might be setting yourself up for disaster.

I'm not saying it couldn't be done but that is a ton of work, money and time for something that "might" work.

I think it sounds like really neat project though.

 

[191Seanymphstriper]

Re: ? Starcraft cc rebuild idea Convert (2) 26 starcraft islanders into (1) 36ft cc

Boat biz .... You dont think 4 feet of rivited and welded aluminum isnt strong enough? Why not? I would think that it would be very strong... Whats your theroy?

 

[191Seanymphstriper]

Re: ? Starcraft cc rebuild idea Convert (2) 26 starcraft islanders into (1) 36ft cc

Thanks for the input Comoxsam, Well I wouldnt just be riveting the floor and sides.


I was also thinking of welding with the rivets and also I would deff be welding the ribs togeather joining them strait threw from bow to stern!

I was also thinking instaed of doing a wood floor or a starboard floor on this rebuild, I was think of welding the floor in fluss using sold sheets of aluminum and making it a self bialing hull.


I figured I would do foam then weld it all up so its almost air tight! Then put a bilge pump and plastic access hole upfront near the bow, and a bildge pump mid center under the center console opening where the controls are and in the stern under a plastic sealed access opening as well as the front...



The purpose for this I was thinking would be to reinforce the hulls togeather adding alot of reinforced strength threw the whole surface!

Also to keep the foam dry from the basic desgin where it wasnt self bailing and everyday rain water etc would run threw the bilge!


And also if you were to buy a decent fiberglass or aluminum plated cc in this size in used good condition I would be looking at at least 35K at the least.

I don't think this build would surpass 15K and thats with used decent 2 stroke outboards...

I can prob pick up 2 used 26 ft islanders for lets say 4K total. I can get some nice older rebuilt 150 hp mercs for about 4K to 4500 from a good friend who is a outboard mechanic and comes across alot of used motors. Thats $8500...

Now I have a friend that will give me the aluminum sheets he has all types of thickness's Thats $0

I have a bunk trailer that can fit up to a 38ft boat. Was used for a 36 scarab that my friend sunk so he can give me that as well he said... Thats $0


Also I have purchased a nice used Center console with windshield that is very big and high and would be great for only $100 on C list!


Im thinking for used controlls, used outboard bracket, 3 new 100 gal fuel tanks, SS hardware, ss cliets and rod holders, paint, ryno liner. Etc etc etc... I can prob keep it under 15K to 20K Tops


Now thats still cheaper then a used 33 to 36 cc,,, And it would be freshly rebult and new looking and have freshly rebuilt motors and well, I would have custom built it! So it would be very uniqe and special to me.








What are your thoughts on that Comoxsam???

 

[Shife]

Re: ? Starcraft cc rebuild idea Convert (2) 26 starcraft islanders into (1) 36ft cc

Ok can you share some phissis on the subject? Like caculated reasons etc?

1. The scantlings of a 26ft boat do not translate into a 36ft boat.

2. Review the definition of scantlings and how it applies to structural engineering.

3. Welding aluminum in a marine application should only be attempted by a professional with the ability to restore the original properties to the substrate metal after welding.

Welding two sheets of aluminum together is easy. Re-tempering the metal to restore its properties after welding is not easy and given the potential for injury/death involving boats I'd say this is not a project for your average DIY'er. The plate thickness is too thin for the increased loading. The realistic costs of making this project actually work exceed what it would cost to build a proper 36ft aluminum boat from scratch.

In short, you probably can't afford to pursue this crazy idea to the end and you will most likely end up with beer can material that cost you far more than scrap value.

 

[jimdd810]

Re: ? Starcraft cc rebuild idea Convert (2) 26 starcraft islanders into (1) 36ft cc

It dosnt sound like a good idea to me either, Youve not mentioned the stringers at all what is the plan for that?

 

[reelfishin]

Re: ? Starcraft cc rebuild idea Convert (2) 26 starcraft islanders into (1) 36ft cc

Several things come to mind right away with this idea.

- The finished boat will be an awfully narrow 36 footer.
- The materials used to build the boat as a 26' boat may not be thick enough or strong enough to endure the added stresses which will be applied by making it 36'.
- Those boats don't have any structural stringers, just deck supports for the most part. You will be relying on the strength of the gunwales and deck to prevent lateral flex.

Do I think its possible to make such a boat float and function, sure, but I have my doubts to how it would look or how durable or safe it would be.
Joining the two halves would require far more than just lining up the rivet holes, plus there will be a seal to deal with. The exposed seam will need to be riveted much like the original transom panel was riveted around the edge. The rivets will need to connect both hulls, and each rib at a perfect fit.
You will have to take many measurements to see if the two hulls will even 'nest' together and if they will lay properly to even look right let alone fit closely enough to be able to seal properly.

All in all it's obviously far more trouble than its worth to do. I'd be more likely to consider such a modification on a glass boat but again, your not adding any width, which with a 10' gain in length, may be needed to maintain stability.

 

[Bondo]

Re: ? Starcraft cc rebuild idea Convert (2) 26 starcraft islanders into (1) 36ft cc

Ayuh,... Just Look at those hulls,...
I've got a 221 Islander,...
It swells at the bow, then tapers, All the way to the transom...
Where are you going to find 10' of it that'll marry up to the same width, anywhere in it's entire length...
It's basically coke bottle shaped...

 

[191Seanymphstriper]

Re: ? Starcraft cc rebuild idea Convert (2) 26 starcraft islanders into (1) 36ft cc

1. The scantlings of a 26ft boat do not translate into a 36ft boat.

2. Review the definition of scantlings and how it applies to structural engineering.

3. Welding aluminum in a marine application should only be attempted by a professional with the ability to restore the original properties to the substrate metal after welding.

Welding two sheets of aluminum together is easy. Re-tempering the metal to restore its properties after welding is not easy and given the potential for injury/death involving boats I'd say this is not a project for your average DIY'er. The plate thickness is too thin for the increased loading. The realistic costs of making this project actually work exceed what it would cost to build a proper 36ft aluminum boat from scratch.

In short, you probably can't afford to pursue this crazy idea to the end and you will most likely end up with beer can material that cost you far more than scrap value.

Thanks for the input!


I know what the meaning is. Thanks, And also im not thinking of building a submarine so I do not need ("tempered aluminum").


And yes I do know all aluminum has tempered properties as its strenghth and heat will weaken these properties from overheat of welding etc!!!!

I think if I do not burn it when im welding and keep it moving the degree in which you would change aluminums temper properties would be enourmous if you do not know how to weld etc yes then this may be a point!

I do not think that running a twisty around the joints will weekin the aluminums temperment properties if done correcyly is all im saying!

And I can weld aluminum better then most so called (proffessionals).

But I am no professional iether!

Also I do not think it will be that expensive as you say at all.

I know alot more then just turning a wrench! And I have alot of good friends to help out with the build!

But I do not know everything thats for sure!

But I have good friends in alot of right places for this build is all!

So without my friends and these forums I wouldn't attempt to build this idea!


And it is posts like yours that make me think about certain things etc.. So thanks!

I can make new ribs and braces and brackets (aka stringers)at my friends sheet metal shop!

He has some serious machines that could bend some aluminum sheets by computer to certain demensions etc!


As far as my finances go. I can afford a new boat. But I choose not to ever buy a new! (unless I win the mega millions)

But honestly I think its a waste of dime to buy brand spanking new when you can buy a couple years old at half the price!


But i think its the fun of the build and the custom uniqe idea that wants me to build this boat...

Im the tpe i get a idea I like to actually do it or at least try to do it!


Thanks for the input though. I was kinda looking for temper decay properties at this diameter in degrees as in FH and preasure breaking ponits (snap point) and aluminum bend stress levels As in inpact force and sheer wieght capacity on a square foot etc!

 

[191Seanymphstriper]

Re: ? Starcraft cc rebuild idea Convert (2) 26 starcraft islanders into (1) 36ft cc

It dosnt sound like a good idea to me either, Youve not mentioned the stringers at all what is the plan for that?

Well i was going to either make new stringers at my friends sheet metal shop which would take countless hours of perswading and grinding and bending,,,, or I was going to do a 6 foot aluminum 3 wall box type plate and go over the stringers lining up and weld then togeather..


Im thinking this may be strong enough with the welded hull to the side wall!

But im not positive

 

[191Seanymphstriper]

Re: ? Starcraft cc rebuild idea Convert (2) 26 starcraft islanders into (1) 36ft cc

Several things come to mind right away with this idea.

- The finished boat will be an awfully narrow 36 footer.
- The materials used to build the boat as a 26' boat may not be thick enough or strong enough to endure the added stresses which will be applied by making it 36'.
- Those boats don't have any structural stringers, just deck supports for the most part. You will be relying on the strength of the gunwales and deck to prevent lateral flex.

Do I think its possible to make such a boat float and function, sure, but I have my doubts to how it would look or how durable or safe it would be.
Joining the two halves would require far more than just lining up the rivet holes, plus there will be a seal to deal with. The exposed seam will need to be riveted much like the original transom panel was riveted around the edge. The rivets will need to connect both hulls, and each rib at a perfect fit.
You will have to take many measurements to see if the two hulls will even 'nest' together and if they will lay properly to even look right let alone fit closely enough to be able to seal properly.

All in all it's obviously far more trouble than its worth to do. I'd be more likely to consider such a modification on a glass boat but again, your not adding any width, which with a 10' gain in length, may be needed to maintain stability.

Hey thanks for the ideas!


Well as far as being narrow I dont think it would be more or less narrow then lets say a 36ft chris craft stinger cc boat

Well I was also thinking for the joining the hull as stated previously with ruber inbetween the 2 hulls with 5200 on all sides...

Riveted togeather......


Then weld the open seems

then on the inner hull weld and rivet som plates at the inner floor seem



Then gluvit on top of everything all 36ft of the inner hull from top to bottom..... And I did state that I know how to weld aluminum fairly well and im pritty seasoned.


I was also going to weld the floor in to give it even more structure and strength


So I was thinking of doinging rivets and welding the halfs togeather plus welded floor plus 6ft stringer brasses welded over top of meeting conjoined stringers!

As far as the strings go I was going to get them as close as possable in diametere and do a 6 foot aluminum brace over welded on and over joining them plus the 6 feet wood reinforce that area for up and over and down wave force im hoping! This is just my idea of how to reinforce it!

These are just my thoughts! I'm thinking this could work... Im sure that I can get it to line up fit and float and look good...

What i am worried about is When I am going over a wave and if I get stuck 75 miles offshore in a very roller type wave were there like 3 feet to 6 ft apart and theres a constant up and over type wave with waves breaking ove rthe bow a little. Like a pound up at the bow... thats my worry... Not doing 60mph over a wake.....


It will take alot of bending and grinding to get all new stringers. But I was thinking if I got a heavier grade aluminum sleeve in that 6 ft lenghth it would be sufficiant enough to reinforce the stringers strength!


But I dont know that for a fact... So what i would need to do is weld a sleeve on one another then remove the stringer in one huge long piece and give it a stress test!


I have a 500 pound friend and he can walk the plank on some horses and kinda see how that goes! LOL

 

[191Seanymphstriper]

Re: ? Starcraft cc rebuild idea Convert (2) 26 starcraft islanders into (1) 36ft cc

Ayuh,... Just Look at those hulls,...
I've got a 221 Islander,...
It swells at the bow, then tapers, All the way to the transom...
Where are you going to find 10' of it that'll marry up to the same width, anywhere in it's entire length...
It's basically coke bottle shaped...

Not when its cut in half! Then you can bend it to where you left off and even if I wanted to recut the transome and go a little wider or thiner I could. Im not worried about that! I am most worried about the force the boat would take in the conjoined area,


Anotherwords when you have a open cut aluminum boat you will deff be able to bend the sides inward and outward as need be. As far as the hull that going on the inside a plazma tourch can make her fit really well if need be im thinking!


But hey what do I know. Im no boat builder! Just a guy with a idea...

Maybe your right! But maybe your wrong... Thats the real question here...

The thing thats making me hesitate by running out and trying this is that, it would be a huge waste of dime it it doesent work..

There is a boat builder about 14 miles from here. I was thinking of giving him some demensions and telling him my idea and getting his input as well!

If the NO's outway the yes's not only in the poll but when I talk with a couple of boat builders who work with fiberglass and plate boats as well as riveted etc... I figured i would get more then 5 opinions from each type of builder just for a laugh etc and see what they say and there thoughts!


And take it from there I guess..

4 or 6K is alot to just throw away and scrap if it doesent work especially when theres starving people out there! Id rather donate the money then just waste it! So No im not running out tm without getting some solid input before I purchase 2 26ft starcraft islanders

 

[Shife]

Re: ? Starcraft cc rebuild idea Convert (2) 26 starcraft islanders into (1) 36ft cc

Read this thread:

http://www.boatdesign.net/forums/boat-design/learning-scantling-part-1-general-arrangement-naval-architects-please-help-30693.html

Here's a relevent quote from that thread:

To be blunt, there are no free rides when it comes to engineering the scantlings for a vessel, especially a blue water yacht. Do the calculations, understand the products, physical limitations of the materials, comprehend the dynamics, concepts, principles, etc., etc., etc. To suggest anything less is asking for a free ride and you'll find most of use will find this insulting. Considering the "profession" is hundreds of years old, I think it's reached maturity, though clearly you haven't, if you expect a free pass on understanding necessary concepts and principles aspects, of the tasks you must perform.

If after reading the above thread you still feel like you know enough to take on this project, then have at it. It's your money and you claim to have plenty which is good. You will need it.

btw... scoffing at the need to preserve the aging of the aluminum plate says you're already over your head. The plate will crack adjacent to your welds and you will have your submarine. The plate used to build these old riveted together Starcrafts is not the same plate used to build a fully welded custom boat. You will be far better off skipping the machismo of trying to weld this and just riveting it together. Visit your local uni engineering dept for some beer can aluminum truss work inspiration and you'll have yourself a long, skinny, twisty, expensive, ummm... experiment.
**
I think it is a neat idea. But... to do this properly will cost A LOT more than the value of the end product and it will be cheaper to build a 36ft aluminum boat from scratch. Extremely advanced engineering techniques would need to be employed to hold the vessel together and keep it from twisting and cracking apart. Weight is your enemy and trying to stiffen aluminum plate that is half the needed thickness will require a ton of bracing.

A stock 26ft Islander is already a twisty beast underway. A shade tree 36ft Islander is a twisty coral reef. Good luck.

 

[191Seanymphstriper]

Re: ? Starcraft cc rebuild idea Convert (2) 26 starcraft islanders into (1) 36ft cc

I was also thinking here this is and would still be a aluminum! Very light. very boyent, and it also will have those very high gunnels adding alot of support as well... I think if I reinforce all the scantling of the vessel this may be alot stronger then to be thought!


I have taken apart a 16ft aluminum starcraft and removed the stringer framing etc... And it seemed pritty darn flimzy to me... I think some better gage over the stringer welded and riveted etc would be way stronger.

Also look at the way the transome on some of these boats are conjoined togeather. Some rubber, corking and wood and rivets.And the strength of the 2 elbows of the side gunnels...


Well the way im thinking of conjoining the 2 hulls would be alot stronger then just that!


So ???????????? Why would it be less or weeker? And also the mid ship wouldnt have direct engine wight plus constant torque of a motor on it as does the transom and the ways its fixed to the hull etc....


Thoughts please??????????????????