# Best resources for learning boat design (Planing hulls)

Discussion in 'Multihulls' started by BananaMan777, Mar 4, 2023.

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### BananaMan777Junior Member

Good day all,

I am relatively new to this site, but I've been researching boat design and the math involved in creating a boat, precisely a Catamaran boat. I have found bits and pieces of the puzzle but I know I am missing quite a few pieces. Does anyone have any good recommendations for books, websites, videos, and/ or eBooks related to basic boat design? I've read threads here on this forum and watched a bunch of YouTube video's but that stuff only goes so far. I'd really like to dive into boat design, learn the theories and take a crack at it. This is just for personal knowledge and not a school project or personal project. I know this is a bold aspiration, but we all start somewhere and I am more so in an inquisitive phase right now and have a lot of questions. Like, is the equation for finding draft/ displacement on a powered (planing) catamaran hull different than that on a conventional planing hull? If the equation is the same as conventional hulls, do you just divide the weight for each hull? I cannot find anything to answer questions like these without coming here. Maybe it's how I am wording it or I am thinking to much into it, idk. Are there any books or videos out there that cover boat design from start to finish for both conventional planing hulls and catamaran planing hulls? I'm new to this stuff so go easy on me. I know I probably just shook the hornet's nest but I am just a curious mind looking for answers. Thanks in advance!

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### oldmultiSenior Member

Bananaman777. I wish you success. Start with the basics, learn about calculating displacement, centre of gravity etc with a basic book like "Skene Elements of Design" (it should be cheap somewhere as its old) then learn about Professional Boatbuilder magazine archives (over 170 PDF magazines) that cover a whole variety of topics from building materials, how structures are built, some power and sailing catamaran design issues etc. After that, there are some specialist engineering issues about structure such as beam design and structurers etc that can be found in engineering books. Then you get to catamaran power design.
This is where the fun begins, designers learn by doing calculations, having something built and then practical experience of how the theoretical calculations match the build. Strangely enough designers who make money of this knowledge are reluctant to hand over the easy "cheat" sheet on how to design a power catamaran structure. Some clues are in the above but look up things like Polynesian Catamaran Association old Sailorman magazines that have a few articles on beam calculation. There are a few web sites by very competent home builders that have done shown calculation processes etc. Google search things like "cross beam design" etc
Finally all of its not hard but just takes time to gather together the information. A short cut is to buy a few "cheap" designer plans from the web to get an idea of some of the issues involved. By cheap, I mean there are some very good professional trimaran designs out there for \$150 Australian. Study Richard Woods design site to get an idea of different styles of power catamarans, look at some of the study plans and build photos as they will help give an idea etc.
Finally, I could guide you to some very expensive books, but until you have the basics in your mind and an idea of what you ultimately want to design, it may be a wasted expense. I have always said the cheapest investment in boat building is a good set of a reputable designers plans.
Good luck.

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### BananaMan777Junior Member

Wow, thank you for the advice, oldmulti! I know it'll be a long road ahead learning the complexity of boat designing but I'm ready to learn. You mentioned buying a set of plans to see the issues involved. What issues are you referring to? I would assume that one wouldn't see any issues with a set of plans since they are worked out already. Are you referring to issues in certain designs, i.e. bad hull shape, no chines, flat bottom, etc.?

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### bajansailorMarine Surveyor

A very belated welcome to the Forum Mr Banana.
Did you ever follow through with the previous thread you started on here re converting a Hobie cat?

I will second Oldmulti's suggestion re Skenes - you can buy a secondhand copy on Amazon for about US\$6.
https://www.amazon.com/Elements-Yac...r/dp/1574091344/ref=sr_1_2?crid=12M6MYVXVGSC3

This wee book by John Teale is also very good, and in particular it explains the basics very clearly and simply.
https://www.amazon.com/How-Design-Boat-John-Teale/dp/157409050X/ref=sr_1_2?crid=3QFMM07LHQJ9J

Oldmulti has mentioned Richard Woods site - here is a link to his power cat designs.
Have a look through all of them - there are some PDF 'study plans' available here that can be downloaded free of charge - download and save as many of them (and any others that you can find on other sites) and establish a library file on your computer for future reference. You can learn a lot even from study plans.

Is your long term plan to eventually design and build a boat for yourself?

Last edited: Mar 4, 2023
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### BarrySenior Member

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### BananaMan777Junior Member

Baja, Thank you for the reply and links to some books; I will look into them. No, I never even started to work on this project because of several reasons. Although a kayak design is still on my wishlist of things to do one day, just not today. Life tends to get in the way of things sometimes. My long-term goal is to gain the required knowledge to start a project and see it through; gaining more experience and knowledge along the way is also a goal. I'm not looking at designing yachts or having a career in naval architecture. I'd just like to expand my knowledge in an area that I am interested in. I've always loved to design things either on pencil and paper or in CAD. I love to draw things I am interested in, mainly aviation stuff. So, I am looking forward to gaining the knowledge/ experience I need to design and build something like a boat. I appreciate everyone's constructive input!

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### oldmultiSenior Member

Bananaman777. The issues referred to are not just about boat shape. The boat structure is all about detail. A hull shell may be 6 mm plywood for a 30 foot sailing catamaran, a lightweight monohull will have 12 mm plywood sides and 15 mm plywood bottom, A low speed 30 foot power catamaran may have a 9 mm plywood hull shell with 12 mm plywood underwing. The hull frames may be 2.5 or 3 foot apart, there may be stringers every 400 mm but each one will be different depending on what the designer thinks is appropriate to obtain hull stiffness to handle slamming loads etc. The full width bulkheads can be a full height or EG aluminum tubes, the transoms can be pllywood, Coosa board etc. It is one thing to calculate the loads, its another to understand materials, the safety factors to include and the structure to support the thrust of outboards, the slamming loads of waves etc.

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### BananaMan777Junior Member

Oldmulti, I completely agree with you. Understanding the materials used, where certain structures are placed, and proper application is just as important as the shape of the design. You can have a beautifully streamlined boat that looks gorgeous, but if you do not understand the importance of structures and processes for said structures, your boat is just a model or a piece of scrap. I know there is more than just reading out of the book to truly learn something; application of the studied material and advice from experienced designers/ builders, like those on this forum, is extremely helpful. Below is the set of books I bought from Amazon and I can't wait to start learning. Hopefully, these will get me started in the right direction.

https://www.amazon.com/gp/product/0070231591/ref=ppx_yo_dt_b_asin_image_o00_s00?ie=UTF8&psc=1
https://www.amazon.com/gp/product/157409050X/ref=ppx_yo_dt_b_asin_image_o01_s00?ie=UTF8&psc=1
https://www.amazon.com/gp/product/1574091344/ref=ppx_yo_dt_b_asin_image_o02_s00?ie=UTF8&psc=1
https://www.amazon.com/gp/product/0070076944/ref=ppx_yo_dt_b_asin_image_o02_s01?ie=UTF8&psc=1

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### oldmultiSenior Member

They will help. But please understand there is very little multihull related information in Gerrs book and any "conclusions" related to hull structure etc is more monohull based information. But Gerrs and Skenes books are excellent starting points.

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### BananaMan777Junior Member

Okay, thank you for the heads up, oldmulti. I am sure I can google it, but do you or anyone else have recommendations on a good book that covers catamaran-style hulls? Specifically a powered planing one? Forgive my ignorance, how much different is a catamaran hull vs a monohull, structurally speaking?

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### bajansailorMarine Surveyor

Please Mr Banana, learn to walk first before running at break neck speed into this.
The four books that you have bought from Amazon will keep you busy for a while - once you have understood the basics of boat design / naval architecture there, and you are still very keen (the maths can deter some folk), then you can think about getting some more complicated books such as Principles of Yacht Design -