Glassing the interior hull

Hello all, I'm preemptively asking a question regarding the interior glassing of the hull for the Chesapeak 17.  I should be getting to this step in the next week or so but would like to get things figured out beforehand...

The instructions and 1 hour full build video on youtube show glass only being laid on the cockpit of the hull.  For the interior storage area glass is only taped over the fillets in the corners and the bottom of the keel.  I've compared this to the method by Nick Schade who will glass the full interior.  I'm curious if anyone has input on this?

Obviously with Nicks strip built method there is no bulkhead on the hull when he lays his interior least from the videos I've seen.  For the Chesapeak the bulkheads are required to get the bottom/sides to shape.  Is there any issue (other than weight) of adding sheets of glass to the storage areas similar to what is done in the cockpit?  


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RE: Glassing the interior hull

I have built two Chesapeakes and you most definately do not need to glass the interior of the storage areas.  That design has glass in the cockpit for added strength and abrasion resistance but that is not needed in the storage compartments where there is little weight or abrasion.  Doing so will add both cost and expense to the build while adding nothing positive.  And the Chesapeakes are heavy enough without adding extra weight.

It is a different story with strip builds because compared to plywood, cedar strip  hulls and decks (pre-glass) are very fragile.  There are some S&G boats that do call for glass on the inside (like the Petrel Play S&G) but those are generally built with 3mm ply as opposed to the 4mm used in the Chesapeake.

Last point is that there have been about 4 zillion Chesapeakes build so if there were any fundamental flaws they have been long ago corrected in the manual.  


RE: Glassing the interior hull

   Sorry, forgot to add that the Chesapeake is a great design.  If you plan to paddle in waves exceeding 2' very often, I would add a skeg.  Much easier to do during construction than as a retrofit.

RE: Glassing the interior hull

   Thank you for your input Mark.  Those are beautiful kayaks!  I am intending to hyrbid the kayak and use bead and cove cedar strips for the deck.  I plan on paiting the hull similar to yours (black) and creeping up and over the deck edge like you did.  Can I ask, did you varnish first, then paint?  That is on my list of things to figure out but since I see you've already done it... :)

Yes, I live in Alaska and I have the smart track rudder system in my kit for helping to navigage my SE waters.  Notorious for current and abupt marine condition changes.

RE: Glassing the interior hull

Generally it is better to varnish the deck first and then paint.  Varnish all the way to the chines on the deck then mask where you want the paint line to be.  If you use a good tape like 3M Fineline you can get a good crisp line.  If you mess it up a bit, it is easy to hide with automotive pin stripes.

Regarding rudder vs skeg:  I have the Smart Track Rudder on 7 kayaks.  It works well in smaller waves but when the waves get over about 2' (depending upon wave shape) the stern mounted rudder gets lifted out of the water and looses effectiveness.  In comparison a skeg is mounted further forward and under the hull so it will always be in the water doing its job regardless of wave height.  Note that race boats designed for waves (like surfskis) use an underhull rudder which is positioned forward like a skeg so that it maintains control.

On four of my race boats,  I can use either a stern mounted Smart Track or an underhull rudder depending upon conditions.  The Smart Track is preferred for races with underwater obstacles which would damage an under hull rudder.  The underhull is faster if not obstacles and better in waves.

Here is a picture of my Spindrift with both Smart Track and under hull rudder installed.  I do not paddle it in this configuration.


RE: Glassing the interior hull

Just one small nit to pick with Mark's otherwise excellent answers. An interior layer of glass has at least 2 positive benefits - much improved puncture resistance and better water resistance.

A puncture is basically caused by a very strong compressive force applied to the outside of the boat. The outer glass layer, which is weak in compression but strong in tension doesn't do much to stop the puncture. The wood, however, is very strong in compression and can resist the compressive force very well. However, if the compressive force is strong enough to deform the wood, its inner surface becomes subject to very strong tensile forces, which in turn cause shearing along the wood fibers. As anyone who's split firewood knows, dry wood is really weak along the length of the fibers, so the the fibers separate and there's a hole in the boat.

An inner layer of glass provides a lot of tensile strength just where the wood is weakest. It resists the tension and therefore the deformation of the wood and prevents the shear forces that tear the wood fibers apart. A single layer of glass inside the boat will do more to stop a puncture than multiple layers on the outside.

The better water resistance comes from 2 effects that internal glass has. First, it results in a more even epoxy saturation over the inside. Second, the aforementioned tensile strength immobilizes the surface of the wood and resists the development of micro-cracks that eventually lead to moisture penetration and wood rot.

So if the boat is going to be subject to a lifetime of hard knocks, extreme thermal cycling and flexing, an internal layer of glass might be a good thing.

FWIW, the weight penalty can be minimized or even avoided with good care and technique during the rest of the build process. My WD12 has a complete internal layer of glass that is not part of the design and still ended up 2 lbs below the design weight. And depending on how and where you're going to be using the boat, a bit of extra weight may not be a problem, it may even actually help. (There, I've said it. I'm a heretic!). if you're not doing competitive racing and you can handle moving the boat in and out of the water, 3 or 4 extra lbs won't hurt anything and may actually help you in a chop.



RE: Glassing the interior hull

I'll side with Laszlo on the durability of 'glass & epoxy on both sides of a plywood panel boat.

If you're planning to use much of the internal storage capacity for carrying stuff besides clothing, eventual wear and tear on an epoxy-clad wood surface will require some maintenance to ensure water doesn't reach the ply underneath.

If weight's an issue when building a race boat this isn't going to be a significant concern. For more casual, routine use, a layer of 2 oz. cloth inside adds durability with less of a weight penalty over 4 oz. cloth but we're talking ounces here anyway, not pounds.  

RE: Glassing the interior hull

  I absolutely agree with everything that Laszlo and Spclark say above.  Adding a layer of glass inside the storage compartments will defiantly make those areas stronger and more impact resistant, and depending upon your skill level as a builder, the weight impact may be small.

The real question is do you need that extra strength?  I submit that under normal conditions, the layup schedule in the manual is more than sufficient.  My 17LT is nine years old and my wife’s 16LT is eight years old.  Both boats were built per the manual and both have held up very well.      

If you have reason to believe that your boat will be subjected to more extreme conditions, then added strength may be worth the added weight, expense and build time.  If you decide that you need a stronger boat, I would suggest that you look at the entire layup schedule for the boat rather than just adding extra cloth in the storage compartments.  

If built per the manual, the Chesapeake has one layer of 6oz on the outside of the hull and one layer of 4oz on top of the deck.  The bottom of the deck is not glassed.  The hull interior has 6oz glass tape laid over all of the fillets and then one layer of 6oz in the cockpit compartment.  This is illustrated on page 92 of the manual.  

If I were suggest a change to the “normal use” layup of this boat, it would be to eliminate the 6oz tape over the fillets and use 4oz glass both inside and outside the entire hull.  This is a pretty standard layup for newer CLC designs what I use on my newer recreational boats.  For a stronger layup, I would suggest either 4 or 6 oz S-Glass on the interior and either 6 oz or two layers of 4 oz on the exterior of the hull.  If you are not familiar, S-Glass is 40% stronger that the normal E-Glass that comes with the kits.  It is also more expensive. 

Lastly, I agree with Laszlo that for a recreational boat a couple of extra pounds is of little consequence, at least while the boat is in the water.  It is another story when it comes to loading for transport.  For me, there is a magic weight somewhere in the upper 40 pound range where loading the boat on the roof racks starts to become difficult.  Where adding a couple of pounds to a 38# boat may not be an issue, those pounds added to a heavier design like the Chesapeake may be.           




RE: Glassing the interior hull

Excellent suggestions Mark_N. You've built enough of of these things to have a great handle on why & how to approach making mods.

I can claim but one CLC build to date yet I used my prior experience when I decided to beef up the sturdiness of my Waterlust canoe with extra 'glass & epoxy on the insides. Even with that, as my first go at stitch'n'glue it ended up within a pound or two of what Dillon targeted the bare hull weight at. NO WAY it's car-toppable either (at my age) so I'm glad I went down that path.  

RE: Glassing the interior hull

Great discussion and insight everyone I really appreciate the feedback.  I live in SE Alaska and this kayak will most likely get used on multi day camping trips involving stuffing gear into an out of the storage compartments.  Additionally our tidal swings can be upwards of 20ft exposing reefs/rocks near and away from shore.  In our frigid and swift SE waters the last thing I want is an errant puncture.

My thinking is that since I plan on using this loaded with gear then some ounces to beef it up is a sacrifice worth making.  I keep going to Nick Schade's builds online where he's putting a glass layer on every surface similar to how you described Mark.  I'll most likely go by the marine store in town to get see what types and weights they have in stock.  Unfortunately, my local resources are limited so if I can't find anything then I'm left with what Amazon is willing to deliver to me.

If you're curious where I'm at in the process right now I've stitched together the hull and have placed in bulkheads and have leveled/faired the boat.  It was an exciting weekend.  I'll most likely be placing fillets in one "Compartment" at a time and fuly glassing the interior.  Due to my garage tempearature I'm using the West System rapid setting hardener that has the ability to cure down to 40 degrees.  I've been keeping my garage at around 60.  My wife will kill me if I keep the garage above 70 during the winter when our electric bills show up.  I'm not too concerned about the blush since 2/3'rds of this work is in storage compartments.  I did find a small Mas Anti Blush epoxy at the store the other day and snatched it.  I figure I'll use this for the deck and cockpit areas and West System for everything else (The hull is going to be painted).


RE: Glassing the interior hull

If present, amine blush will inhibit proper adhesion of epoxy and paint on epoxy.

It's not at all hard to remove, simply requires 'scrubbing' thoroughly with plain water-dampened synthetic abrasive material I've provided more info above in previous posts, then a thorough wiping down with clean cloths.

Even simply clean, water-dampened cotton cloth will effect removal, it's that important for good bonding of both additional epoxy layers as well as finishes like paint and/or oil-based varnish. 

RE: Glassing the interior hull

   Thank you for the clarity on that.  I'll ensure to go through that step in the process.


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