SLX 3 build

Outboard designs up to 14'

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Hoffer
Posts: 23
Joined: Sat Jan 05, 2019 12:00 pm
Location: Ontario, Canada

SLX 3 build

Post by Hoffer » Sat Jan 05, 2019 1:23 pm

Hello,
New member,first build.
I designed the SLX 3 myself, it is modeld after off shore racing cats.
It is ply on frame construction, loa is 12' with a beam of 5.5'. I plan on having left hand drive with controls mounted in centre consoler, powered by a 60 plus hp outboard.
Attachments
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20181116_113458.jpg

Hoffer
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Joined: Sat Jan 05, 2019 12:00 pm
Location: Ontario, Canada

Here are some more pics.

Post by Hoffer » Sat Jan 05, 2019 1:49 pm

Bulkheads are 3/4"
Attachments
20181212_101635.jpg
20181208_162449.jpg
20181208_164235.jpg

Hoffer
Posts: 23
Joined: Sat Jan 05, 2019 12:00 pm
Location: Ontario, Canada

Re: SLX 3 build

Post by Hoffer » Sat Jan 05, 2019 1:53 pm

Taking shape.
Attachments
20181212_101612.jpg
20181223_184158.jpg
20181217_134555.jpg

Hoffer
Posts: 23
Joined: Sat Jan 05, 2019 12:00 pm
Location: Ontario, Canada

Re: SLX 3 build

Post by Hoffer » Sat Jan 05, 2019 2:02 pm

The plan is to skin the boat with 1/4" then add minimum 1/16" to 1/8" line-x ultra. The line-x will strengthen, seal and protect against abrasion........that's the plan as of now.
Attachments
20190104_143425.jpg
20190104_143416.jpg

Hoffer
Posts: 23
Joined: Sat Jan 05, 2019 12:00 pm
Location: Ontario, Canada

Re: SLX 3 build

Post by Hoffer » Mon Jan 07, 2019 3:52 am

After reading some posts on hull thickness, I am now thinking 1/4" may not be enough. I am worried about making the curves for the front sponson bottom as well as front of tunnel bottom. Is there a span between bulkheads that would work for 1/4 inch or should i try another method for skinning the hull?

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DrBryanJ
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Re: SLX 3 build

Post by DrBryanJ » Mon Jan 07, 2019 8:46 am

On the malahini there is roughly 30+ inches from frame to frame. The sides are 1/4 ply. The bottom is 3/8 ply.
Bryan

Building a malahini "Mona Lisa"

My wife said "If I build a boat, she's getting a divorce."

BillW
Posts: 147
Joined: Sun Oct 05, 2008 8:03 am
Location: Seattle, WA

Re: SLX 3 build

Post by BillW » Mon Jan 07, 2019 9:17 am

Looks like it has 2 steps in the bottom. Am I seeing that correctly?

Hoffer
Posts: 23
Joined: Sat Jan 05, 2019 12:00 pm
Location: Ontario, Canada

Re: SLX 3 build

Post by Hoffer » Mon Jan 07, 2019 9:26 am

Yes, I am trying to add some venting rearward. The idea is to trap some air....like larger off shore cats.

Hoffer
Posts: 23
Joined: Sat Jan 05, 2019 12:00 pm
Location: Ontario, Canada

Re: SLX 3 build

Post by Hoffer » Mon Jan 07, 2019 9:32 am

Thank you DrBryanJ.
I will take a look at that boat, the largest spot for me to cover on the sponson is 30" x 17". I'm thinking 3/8" is the way to go as I fell like the boat may achive 50 mph +
I am sure the 1/16" line-x finish will be extremely tough,this is why I was originally thinking 1/4"........I would also like to be able to stand on the decking without worrying about its strength.
The frame of the boat is extremely solid as it sits today, I feel the sheathing should tie it all together nicely.
It is a huge experiment for me as I wanted to build something that was completely my own from concept to completion,all while trying new techniques along the way.

DSR
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Joined: Mon Mar 21, 2016 8:11 pm
Location: Allegan, Michigan

Re: SLX 3 build

Post by DSR » Mon Jan 07, 2019 9:25 pm

Hi Hoffer,

That's a pretty cool looking cat project you've got going on.
A couple questions and suggestions if I may?

First, on your question regarding planking the hull. I looked pretty closely at the pics and I didn't see any longitudinals, or battens, between the shears and the keels on the sponsons (or the tunnel area) to attach the ply planking?. Are there battens and I just didn't catch them? Even with 3/8 ply, you would still need battens to support the ply between the frames, and with battens you should be able to skin the hull with 1/4 marine ply with the frame spacing it looks like you have.
I also noticed that most, if not all, of the frames are plywood, and there are a lot of the joints and fasteners are into the endgrain of those ply pieces. Definitely want to keep an eye on those joints as ply endgrain doesn't hold fasteners very well at all.

Second would be on using Line-X to sheath the hull. Line-X is very tough material and very abrasion-resistant, but would add very little structural strength or stiffness to the hull. In my experience, sprayed polyurethane coatings are by themselves, very flexible. It's also going to add a lot of weight to the build.
What kind of bare hull weight are you planning on for it?

Third would be the steps in the sponsons. I was wondering if you're familiar with how critcal placement and shape / size of the steps are in how the hull will behave at higher speeds?

Please don't get me wrong Hoffer. I'm not trying to pick apart your design and I'm definitely not, and would never claim to be any sort of naval architect, but I have spent a ton of time and effort (and more money than I care to think about) in working out the bugs in my own design, and I'm just trying to pass on what some very knowledgeable people helped me with during the process of creating mine.

Thanks Hoffer,
Dave
DSR Performance - Home of yet another jet TNT build :D
Codename "Just A Little....."
viewtopic.php?f=23&t=29753

Hoffer
Posts: 23
Joined: Sat Jan 05, 2019 12:00 pm
Location: Ontario, Canada

Re: SLX 3 build

Post by Hoffer » Tue Jan 08, 2019 3:56 am

Hello Dave,
Thank you for your help.
I joined the site for this very reason, there is a wealth of knowledge here I am hoping to tap in to. This is my first build and wanted something different that I could call my own.
As far as battens, I am trying now to figure out how many I need the correct locations and spacing. The frame as it sits now is very solid and I should be flipping it soon to start on the bottom.
At this stage the design is evolving as I build, this is why I appreciate all the help/constructive criticism I can get from people like yourself.
The Line-X idea came from research as well as use of the product for other projects.....and wanting to try something a little outside the box. As far as weight goes I am thinking it should come in at 350 lbs give or take, as it sits now it is roughly 160 lbs. In the end I am not shooting for a super light race boat, more like something in between that has the looks and will run well in cottage country lakes.
The sponson steps are something I wanted to try, I did do some research on them as well. The placement of the steps I based on what I have read and scaling down of proven designs. Will it work? I think so. At the end of it all I am just having fun trying to incorporate design elements from larger faster boats.
I'm sure a lot of what I am doing here may not be the conventional way of building, the first idea actually came from the process R/C cats are assembled. The bulkheads are all one piece slid into place on the two main frames, once the pieces were cut the frame went together in an afternoon.

Thanks again Dave for taking a look

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hoodman
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Re: SLX 3 build

Post by hoodman » Tue Jan 08, 2019 9:15 am

Isn't line-x super bumpy? I don't think I'd want that on my hull. It would probably be fantastic for a cockpit sole or decking.
Matt

Building a Geronimo......!
viewtopic.php?f=2&t=25139

Hoffer
Posts: 23
Joined: Sat Jan 05, 2019 12:00 pm
Location: Ontario, Canada

Re: SLX 3 build

Post by Hoffer » Tue Jan 08, 2019 1:15 pm

The newer Line-X ultra can be applied fairly smooth. I am in the process of getting some test pieces to play with.

Axis
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Re: SLX 3 build

Post by Axis » Sun Feb 03, 2019 3:03 pm

Very interested in this, following. kinda wanna built one of these myself now that Ive seen it, lol! :D

Hoffer
Posts: 23
Joined: Sat Jan 05, 2019 12:00 pm
Location: Ontario, Canada

Re: SLX 3 build

Post by Hoffer » Tue Feb 12, 2019 4:17 am

Image
Tunnel and sponson bottoms are on, 3/8" okume.
Attachments
20190211_162621.jpg
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