Slingshot 19 Trimaran Plans

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18' 10"/5.74m
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  • Top Speed (typical) = 14 mph
  • # Of Occupants = Two (with option for three)
  • Length Overall = 18’ 10”
  • Beam Overall With Standard Non-Folding Akas = 12’
  • Beam With Optional Folding Akas = 7’ 2” Closed, 14’ 6” Open
  • NOTE: You get my folding aka plans FREE with your purchase of Slingshot 19 Plans. (The cost is $19.97 if purchased separately)
  • Main Hull Beam = 26”
  • Length Of Amas (outriggers / floats) = 18’
  • Weight Of Main Hull 125-150 lbs (57-68kg) depending on plywood choice
  • Weight Fully Rigged = approx. 225 lbs (102kg)
  • Draft Fully Loaded = 5” with one aboard, 6” with two, 7” with three.
  • Sail Area = from 107 sq ft (with base rig) to 148 sq ft (with sloop rig)
  • Sail Rig Type = several options, both stayed and unstayed (freestanding)
  • Mast = aluminum tubing, either unstayed (freestanding) or stayed.
  • And FREE EMAIL SUPPORT for your build – no matter how long it takes!

Do you want to go fast in comfort and stay dry? Do you like amazing stability and great seats? Would you like to sail and even tack with both hands free to shoot videos, eat your lunch, take off your jacket, or put on sun glop? And wouldn’t it be cool if there was no way the boom could ever hit you in the head?

Welcome to the ‘Slingshot 19’ trimaran!

The ‘Slingshot 19’ is basically a 2-seat version of the ‘Slingshot 16’ trimaran. And the ‘Slingshgot 19’ can carry 3 people if properly configured. It is approximately 15% bigger in all dimensions than the Slingshot 16, and is about 30% heavier. It has a wider open beam (if you go with the optional folding akas), and can it carry significantly more sail.

Slinghsot 19 With Optional 148 sq ft Sloop Rig

The two biggest factors in deciding to go with the Slingshot 19 are:

  1. It’s a two (or three) seater, so you can sail it either alone or with a passenger or two. The primary seat slides to one of three positions, to keep the boat in perfect trim with either one or two aboard, or one more on the optional tramp.
  2. You also get the option of having straight one-piece tubular akas, or you can have the proprietary “folding” aka system. With the folding akas, the amas swing in alongside the main hull so you can quickly reduce the overall beam from 14’ 6” to just 7’ 2’. You can be sailing in well under 10 minutes!

Slinghsot 19 With Optional Folding Akas and New Paint Job!

The normal top speed is around 14 mph, just as with the Slingshot 16. But the Slingshot 19 is smoother, quieter, quicker in light air, handles rougher water better, and just “feels more stable” in virtually all conditions. I also have designed a side-mounted motor mount, and often bring along a small outboard, just in case the wind dies.

Just like the Slingshot 16, the 19-footer readily points higher than 45 degrees, and turns on a dime. It can be launched in 4” of water and sailed away - upwind - in just 6”.

And thanks to its twin leeboards, I have watched the ‘Slingshot 19’ go 9 mph UPWIND – 45 degrees off the wind – in just 12 mph of breeze. You will be amazed at how easily it passes other sailboats – especially when close-hauled! Here's a short video of the Slingshot 19 trimaran in action, cruising in light air at the mouth of the Manatee River, near Tampa Bay, FL.


The amas for the Slingshot 19 are a full 18' long. This long length, plus the well-rockered, V-hull ama design provides the perfect combination of smoothness, buoyancy, quietness, and splash-free sailing.

Although I have three other trimarans ready to sail (two 16-footers and a 24-footer), it’s the Slingshot 19 that I grab when I want to bring along someone else, or go out in rough weather. And if you’d like to teach others to sail, this is the ideal boat. It delivers sizzling performance with two aboard, yet is virtually incapable of capsizing or pitch-poling.

Slingshot 19 With 107 Sq Ft "Base" Sail Option And Non-Folding Akas

Basic Materials List:

  • (6-1/2) sheets of 6 mm ply (recommended for all main hull panels)
  • (5) sheets of 3 mm ply
  • (½) sheet of 1/2” ply (This plywood should have 4 or more plies)
  • 8 linear ft. of 1” x 6” lumber (3/4” x 5-1/2”) clear or nearly so
  • 80 linear ft. of 1”x2” lumber (3/4” x 1-1/2”) clear or nearly so

NOTE: The original Slingshot 19 (and amas) seen in these photos was built from plywood (3mm and 6mm) costing about $12 and $21 a sheet, respectively. You can also spend the extra $ for okoume or some other pricey species of plywood. As long as the glue is waterproof, you can use any ply you wish.

"Hey got the plans downloaded the other day. Can't express how happy I am with them. I am so grateful for the time and that went into them. Now I just have to get them printed etc. and the fun can start. Thanks for everything. I will stay in touch and send questions your way as they arise. Thanks again..."
- Wendell Bailey

Plans Include:

  • Three extremely detailed Construction Plans manuals with a total of more than 240 photos illustrating the complete building process, with nearly more than 10,000 words of explanatory text by me, Frank Smoot.
  • Separate Drawings Plans manuals with more than 100 superbly detailed, multicolor CAD drawings by Jerome Delaunay.
  • Best of all, you get FREE EMAIL SUPPORT for as long as it takes to complete your build!! Just contact me at with any questions you have - and expect a quick response.
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Additional Information

Designer Name:
Frank Smoot
Sail area (Imperial / Metric):
107 sq ft / 9.9 sq. m to 148 sq ft / 13.75 sq. m
Rig Type:
Keel Type:
Length (range):
16' - 23'11" / 4.88m - 7.29m
18' 10"/5.74m
Length at Waterline:
18' 10"/5.74m
Hull Weight:
200 - 999 lbs / 90.72 - 453.14kg
Estimated Hull Weight:
225 lbs/102kg
Under 6" / 15.24cm
Unloaded Draft:
5"/127mm - 7"/178mm
Primary Material:
Marine Plywood
Method of Construction:
Stitch and Glue
Hull Type:
Hull Shape:
Power Source:
Built-in Floatation:
Unit of Measure:
Instruction Manual:
Step-by-Step Instructions
Lofting Required:
Recommended Experience Level:
Designer's Thoughts on Experience Level:
Chuck Leinweber's suggestion
Boat Type:
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