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18’ scooter build

22K views 73 replies 12 participants last post by  Big_lj 
#1 ·
Hello all figured I would post this build up as it will be followed by a 12’ model.
The build is mainly for protected waters, I wade fish a lot as well as flounder gigging and like the simplicity of the design. I use a lot of core strengths from previous builds as well as lamination schedules. Some trial and error and some just well over built as i am guilty for sure. I look forward to comments good and bad I’m here to learn as well as hopefully encourage others to build.

Currently building an 18’ Texas scooter from scratch.

Length: 18’
Bottom: 84”
Beam 96”
Sides: 13”
Keyslot transom
Pocket tunnel
Projected draft: 3-4”

Materials:
Marine Epoxy
1/4, 3/8 and 3/4 marine ply
1708 biax
12 oz and 1708 tabbing 6”
Wood flour
Lots of patients
 
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#3 ·
I originally laid the hull out to be 16’ but my son encouraged me to add two more feet. Here is the initial layout with cheap ply making patterns.
Wood Plywood Architecture Hardwood Sport venue
Vehicle Table Boat Watercraft Metal
Table Wood Plywood Architecture Floor
 

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#5 ·
Once I laid out the model and figured angles and lines I started on the actual build.

Disassembled and laid out patterns on Marine ply.

Bottom section is of 3/8 meranti
4 and 1/2 sheets with puzzle joints
Wood Hardwood Table Furniture Floor

Joints assembled with thickened Epoxy and one layer of 1708.Center seam butted, glued and taped.
 
#7 · (Edited)
Set up bottom on table and started assembly and laying out sides.

I am using a stitch and glue method and I’m actually building it upright. This allowed for design as I go as per sides, stringers and framing.
Motor vehicle Asphalt Crash Automotive tire Mode of transport
Room Furniture Beam Floor House

I wanted a more rounded custom look over the typical squared bow section. Took a little figuring and practice but I like how it turned out. Seams glued up
 
#8 · (Edited)
Transom section in and taped, used two laminated layers of meranti 3/4.
Plywood Wood Room Furniture Lumber

Once sides and transom setup I cut out for Keyslot transom. I kicked this option around a bit due to the loss of draft however the benefit well outweighs the loss on this build. Being so wide I don’t see it being to much of a loss. It should create some drag and suction to keep this girl on the water .
Wood Soil Roof Concrete Vehicle

Clamping board is made up of two layers of 3/4 meranti laminated. The knee braces are two layers of 3/8 meranti laminated. I have found when you laminate it makes for a super strong section especially in areas of sufficient stresses. The lower section shows the cutout for the planned tunnel. The transom section will be completed with a full transverse section of 1/2” to mirror clamping board and will run from P to S to complete the box frame. Hope this makes since.
Wood Furniture Table Plywood

Gaps left to be filled with thickened Epoxy, gaps always good when filled with thickened Epoxy to me it’s a stronger joint and make it easy to round the corners for taping and glassing.
Wood Hardwood Floor Beam Lumber

Keyslot all glued up and corners rounded ready for tabbing. All transom area is taped with 1/2 fillet, 3 offset layers of 6” 1708 biax. Next cover transom section tabbed into hull bottom overlapping 10”.
 

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#9 · (Edited)
Tunnel cut out and installed. Glued in and ready to prep for fillets and taping. Will be taped in with 3 offset layers of 1708 then covered with 2 layers of 1708. This is a high stress area and should be compensated for. The 2 full height center section stringers will fall each side of tunnel making it one unit. Then I will add two additional full height stringers one each side. So a total of 4 stringers planned with transverse frame every 30” creating egg create framing.
Wood Floor Hardwood Plywood Lumber

Floor Wall Wood Hardwood Furniture

Beam Wood Table Room Architecture

Once framing is complete I will flip and cleanup and complete bottom section, lamination schedule for bottom:
Seams, 3 layers of 1708 6” offset
Bottom:
Two layers of 1708 cloth overlapping center section 10” and over the sides and transom. Then fair it out and add four coats of graphite Epoxy.
 
#15 ·
I don’t think it will be necessary on this hull, the tunnel length is 46” which is less than 1/3 of the hull length I also added 1.5” to the height. This tunnel is pretty proven with a few other builds. Once flipped you will see that I have put a 4” radius on corners as well. Not to concerned with drag. This will be a learning curve and will modify it from here. I don’t like vents as they cause the water to become aerated and the fact of another hole in the hull

I have already started laying out a 10’ and 12’ versions I’m building for my son, will post on it as we get started.
 
#16 ·
So the benefit of the vent is to reduce the drag? Sorry not trying to be a wise guy just trying to understand, the way I have read about it, is it reduces the suction to the bottom of the hull allowing it to release a lot like taking the finger off the end of a straw when you pull soda outa your glass with your finger on it?

Another question because you've obviously built a boat or two before and sorry again for all the questions just trying to learn. The benefit of the rounded corners is they provide less drag or most likely turbulence as well?

Thanks again for any help
 
#17 ·
No worries lol I’m learning everyday. Yes the venting release the suction thus lessening the drag. One thing I understand about venting is if you run shallow all the time it’s not worth it, I run skinny thus I catch fish as per fishing in backwaters other can’t so I like a tunnel for what it was designed. I have also seen were venting can cause dirty water causing the prop to slip. These boats are sleds if you will I’m not looking to go 50 but more so looking for performance. Most tunnels I’ve seen vented only gain a couple MPH not worth it to me for the work and extra holes. Just my 2 pennies
 
#19 ·
So let me ask you something more, since we are talking about tunnel's, is there benefit to having a more gradual tunnel, or should a tunnel be more abrupt like yours is? The reason I ask is I've seen production models that tend to have a more gradual tunnel starting from nothing and in 40 or so inches reaching 3 inch or whatever type of depth they want in the tunnel.
 
#21 ·
The shape has a lot to do with the hull design, I’ve used this style tunnel and it was developed by BBC and is proven, provides clean water with minimal drag. I’m not by no means a designer and there is a whole world of research on this subject but no real answer. I go with experience and hands on proof. The shape has a lot to do with what type wake you need exiting.
 
#23 ·
Here's a clip of a vented tunnel just to show what East Cape suggests is the benefits. You can really hear the difference but like you said it has a lot to do with how you designed the tunnel as well.

Yep it released the drag however if you know what your looking at the motor is at basically its lowest point at which point you would never run a tunnel hull if you know what your doing. You can make a standard hull do that with a jack plate or by having your motor mounted wrong. It all comes with sacrificing something but in general in my 27 years I’ve seen a lot of tries at a perfectly designed tunnel and have yet to see it. All hulls have their sweet spot you just have know what your looking for and find it.
 
#24 ·
True cool, I'm just showing you something I saw. I have a jackplate on my non-tunnel hull currently and I get it, it was at it's lowest position just food for thought. So a deeper tunnel that has a more direct path theoretically would have less turbulence by the time it gets to the end of the hull?
 
#25 ·
Also there was a plywood boat that was built back in the day called The Grass Slipper, he did a really intreasting way of venting a tunnel without a hole in the tunnel. He took PVC pipe cut it down I'm gonna show a pic, it also provided the rounded edges like you were talking about to clean up the water flow.



 
#34 ·
Also there was a plywood boat that was built back in the day called The Grass Slipper, he did a really intreasting way of venting a tunnel without a hole in the tunnel. He took PVC pipe cut it down I'm gonna show a pic, it also provided the rounded edges like you were talking about to clean up the water flow.




@Brett - would you be so kind as to share your experience with this.
 
#26 · (Edited)
Looks like a smart way of doing it. I’m just not a big fan of the vent, with a pocket tunnel your going to loose something no matter what you do. Now if you speak of a true tunnel hull then you have a whole different beast, self venting as the hull planes. I’ve had these tunnels in 3 different boats and have never had any problems. We have yet to mention the cavitation plate
 
#27 · (Edited)
Here lies the answer to a lot of issues with a tunnel by keeping the wake were it belongs at the prop and intake.

Vehicle Machine Wheel

I’ve found that if you keep the top of the tunnel parallel to the planing surface you will get the best performance. I’ve seen the ones such as path finders and others that have offset side and rounded tops they always seem to create such if a rooster tail wake thus spraying water up and in the boat.
 
#43 ·
Here lies the answer to a lot of issues with a tunnel by keeping the wake were it belongs at the prop and intake.

View attachment 129126
I’ve found that if you keep the top of the tunnel parallel to the planing surface you will get the best performance. I’ve seen the ones such as path finders and others that have offset side and rounded tops they always seem to create such if a rooster tail wake thus spraying water up and in the boat.
I’ve found that the cavitation plate works best if it extends farther back behind the prop where it can capture the thrust.
 
#28 · (Edited)
Got the rubrails build and installed last night, glad to see the rain finally.

Build the rubrails out of two offset laminate layers of 3/8 meranti glued up with thickened Epoxy. Really stiffened up the sides.

Up early this morning for some sanding, prep for glassing the inside. I’m drinking my coffee slowwww this morning lol as I always look forward to sanding.

Just a little trick for those of you that don’t know. When sanding fiberglass prior to starting strip down and cover up your skin with a dusting of baby powder. It will keep the fibers from getting into your skin for the most part.
 
#29 ·
Got one layer of glass in will finish up in the morning and post up pics.

One other tip for Epoxy users that don’t know, vinegar removes Epoxy form you skin safely and quick, lol unless your allergic to it.

I always keep a jug in the shower when I building a boat. Lol so ones always there. My wife says you ain’t selling this one hence she is my flounder gigging partner.
 
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