how to lighten a boat useing diffrent materials

cad22000 · Post by **cad22000** » Tue Feb 26, 2013 11:16 pm

hello everyone , i am looking into building the sea angler , i am looking into the foam core sandwich construction and wanting to trim the weight of the construction of the boat , my question is can i use a 3M bulker mat instead of 1oz mat , can i use S-2 glass instead of mat , what can i substitute if anything with lighter fabrics and still get the strength or am i missing the big picture on the mat , i am going to use the vacuum bag method on the entire process any input would be helpful i am having a hard time in finding answers online Thank you

jamundsen · Post by **jamundsen** » Wed Feb 27, 2013 5:19 am

Hi cad22000
This is a tough one to answer. I have been looking for some of the same answers and you are right, there is little to no information available. Not many people are building in glass. My feeling is if you are new to this like me then follow the instructions carefully as you need the strength that the different materials create when used together. Again I dont know very much so I will be following you as you learn and tell us. I purchased a vacuum pump so I could experiment but all Ive done is create more questions. Someday i want to build the cruise missle and it needs to be strong and light. good luck on your build

Mr Hot Rod · Post by **Mr Hot Rod** » Wed Feb 27, 2013 9:21 am

cad22000 : Welcome to the Forum ! Now that's a big project ...

If you don't have it already, a great reference book is Fiberglass Boatbuilding for Amateurs by Ken Hankinson. Molding techniques and materials are discussed in great detail.

Fiberglass Boatbuilding for Amateurs by Ken Hankinson

Some of the topics covered include :

• Sandwich core materials and priciples
• Foams for sandwich cores
• High modulus materials and specialty reinforcements
• Vacum bagging methods with sandwich cored hull

For example, you'll find comparison data of sandwich laminates with conventional fiberglass, Type S-500 Fiberglass and graphite ORCOWEB.
Total laminate weights (PSF) are 3.71, 1.51 and 1.10 respectively. (Reference : Figure 21-5, Page 257).

You may glean some info from the Bandido's hull laminate material estimate. Sandwich core and high-tech version are covered :

Bandido - FG Bill of Materials

Good luck with your project and don't forget to post some pics along the way !

John : No excuses now -- We want to see that Cruise Missile soon ...

___________________
Paul Kane Chelsea, PQ

Building the Glen-L Hot Rod

kens · Post by **kens** » Wed Feb 27, 2013 4:47 pm

Personally, I think if you want it light, build it in wood.
The boats on this forum are by a wide margin, wood. And all our boats are lighter than any fiberglass comparable boat.
For example, take a chunk of SOLID fiberglass, and a chunk of solid wood, and toss both off the end of the dock.
Tell me which one hits the bottom first.

Post by **Bill Edmundson** » Wed Feb 27, 2013 5:00 pm

A typical 20' wood with fiberglass skin boat might go 2000 pounds. The same boat in glass will go about 5500 pound. Foam core somewhere in-between.

I believe these wood boats are amazingly strong.

Bill

Lowka53 · Post by **Lowka53** » Wed Feb 27, 2013 6:29 pm

the 29 foot jubilee hull weights in at 2100+ or - it is wood construction with fiber glass

MultiTec · Post by **MultiTec** » Thu Feb 28, 2013 2:21 am

you can save some weight using Kevlar and Carbon fabric of equal strength but lighter weight

also prep yourself the lightest foam you can find

kens · Post by **kens** » Thu Feb 28, 2013 3:43 am

MultiTec wrote:you can save some weight using Kevlar and Carbon fabric of equal strength but lighter weight

also prep yourself the lightest foam you can find

and even with these modern materiels, you must vacuum bag the entire process to get the final results.

Kevlar & carbon fiber & foam core still is not lightweight in a hand layup process. It must be vacuum bagged all the way to be light.

MultiTec · Post by **MultiTec** » Thu Feb 28, 2013 4:04 am

kens wrote:
MultiTec wrote:you can save some weight using Kevlar and Carbon fabric of equal strength but lighter weight

also prep yourself the lightest foam you can find
and even with these modern materiels, you must vacuum bag the entire process to get the final results.

Kevlar & carbon fiber & foam core still is not lightweight in a hand layup process. It must be vacuum bagged all the way to be light.

i was going to add that

and you need a good resin pump

Bob Perkins · Post by **Bob Perkins** » Thu Feb 28, 2013 5:50 am

I built my boat using vacuum bagging.
It is a very light hull.
I haven't found a set of scales I can use to get it all weighed yet - I estimate 2,400lbs for 23' boat.

I'm sure I saved plenty of weight in epoxy alone vacuuming the hull - and it is extremely stiff.

Beyond that - these boats were designed to be a certain weight and balance. Messing with the intended designs can have unintended consequences.
be careful.

kens · Post by **kens** » Thu Feb 28, 2013 4:59 pm

Bob,
I'm with you. Your boat is likely about that weight. I weighed mine and it was 2,480lbs with 11gallons gas, up and running. I know you got more interior fabric, foam & stitches than me, but I got much higher freeboard plus heavier shaft strut & rudder,
At the end of the day I bet both our boats are comparable weight plus or minus 200lbs. I am at 24'8" open cockpit.
I weighed the whole rig boat, trailer & truck at the local truck stop truckers scales.
Then launched the boat and tied it up at dock. Drove the empty trailer back to truckstop for a re-weigh.
The math gave me 2480lbs.

As Bill mentioned above, a fiberglass boat may be 2x heavier than one of our wood boats. I know that I took the old 'glass hull that my motor came from, and had to pay the junkyard to accept 1900lbs of stripped out 'glass hull. it was a 19' boat.

When I had my hull equally stripped down as the 'glass donar, my wood hull was 6' longer and 700lbs lighter.

cad22000 · Post by **cad22000** » Thu Feb 28, 2013 9:57 pm

hello all , thank you for the impute i have considered Kevlar and carbon fiber, i do have the fiberglass book. with using carbon fiber though it is hard to get the real strength out of it with out engineering the stresses and putting the warp and weft in correct me if I'm wrong on the terms i just know you have to lay it in a certain degree and schedule to get the strength out of it and not to crack it from being to stiff i could be wrong , i am looking to lighten the hull and subsequently lighten the superstructure and interior to keep it in balance, i understand composite structures and the process better then wood and better familuar and feel more comfortable with fiberglass , i know with the bagging process just even if you use the same materials will be lighter and better quality then hand lay up , could i substitute the mat with a lighter cloth or a bi axial cloth that will give better strength , if so what weight what type Kevlar,s-2 ? and also with the core material what is the lightest foam out their i am having a hard time finding weight of a sq ft or some form of weight , could i use nida core or similar i know we use it extensively in the aviation world. i agree on the vacuum bag process it is the only way to come close to achieving my goal i will look at the book again and look at that section

Mr Hot Rod · Post by **Mr Hot Rod** » Fri Mar 01, 2013 12:48 pm

1) Could I substitute the mat with a lighter cloth or a bi axial cloth that will give better strength , if so what weight what type Kevlar,s-2 ?

In polyester layups, mat provides a bonding interface between layers of woven materials like cloth and woven roving. If laminating with epoxy, the mat can be omitted or it can be replaced by light cloth.

2) With the core material what is the lightest foam out there. I am having a hard time finding weight of a sq ft or some form of weight , could i use nida core or similar ?

Not much variance in foam core weight. Product weights are stated on Noah's Marine website. Here's some data comparing Nida Core™ and CoreCell™ foams :
Note that when its encapsulated in a laminate, Nida Core™ is recognized by the US Coast Guard as a primary flotation material.

For alternate laminate schedules, you may want to contact Glen-L or post your questions over on the BoatDesign.net Forum under the Fiberglass and Composite Boat Building topic.

____________________
Paul Kane
Kane Custom Boats Ltd.
Chelsea, Quebec

Building the Glen-L Hot Rod : http://www.kanecustomboats.com

Glen-L Boat Video Directory : http://www.kanecustomboats.com/pages/vi ... ctory.html

R19demA · Post by **R19demA** » Thu Dec 11, 2014 6:14 am

Yes, pictures always help. It would be best if they were of the inside of your actual boat showing accessibility of the bottom. Can seats and other stuff be removed?

Post by **billy c** » Thu Dec 11, 2014 7:00 am

welcome R19
this is a pretty old thread.
it would help if you start a new thread telling us a little about what you are interested in building. ...then we like to share pictures

-Billy

Glen-L.com