PDA

View Full Version : Mini tugboat built with regular outdoor plywood instead of marine plywood



mau_ben
02-04-2017, 11:47 AM
I have heard many different views about marine plywood vs regular external plywood for boat construction. I'm certainly not an expert by any means, but if the plywood is fully properly covered with Fiberglass, I think marine plywood may just be a waste of money if the boat is going to be painted.
I built this mini tugboat last year with regular external plywood and I'm quite happy with the result. In my lake adventures last Summer, the boat took quite a beating a few times on lake Muskoka when the water was very choppy and it survived quite well without any problems.


I did make some slight modifications from the plans to improve the steering at low speed and I added some more buoyancy at the back to raise the back end. This is only useful if you want to carry 2 adults in the back seats (back seats are not specified in the plans). The enclosed video was made before the extra buoyancy was added. Aside from that, it was built pretty much as per the Berkeley Engineering plans.


https://youtu.be/tzeHwGczXLM

https://flic.kr/p/MmsGr3

https://flic.kr/p/Mmm4nK

Maurice

Thorne
02-04-2017, 12:38 PM
Time will tell. Let us know how it works out after a few years.

Cute boat! https://c2.staticflickr.com/6/5641/29767593404_3d65fc0eee_b.jpg

Breakaway
02-04-2017, 03:08 PM
A beautiful build. You should be proud.

To address your question about plywood, I can only say that the cost difference between marine ply and exterior ply seems like a lot when comparing just the plywood. But, when I consider paint, and glue, and fasteners, and fittings, and fixtures and engines, etc., the price difference is so small a percentage of the total build as to be negligible.

Kevin

nedL
02-04-2017, 03:16 PM
Adorable!! I think you made a good choice, for something like your mini-tug you will likely never see a difference between 'marine' and a good grade (ACX or BCX) "exterior".

mau_ben
02-04-2017, 07:08 PM
A beautiful build. You should be proud.

To address your question about plywood, I can only say that the cost difference between marine ply and exterior ply seems like a lot when comparing just the plywood. But, when I consider paint, and glue, and fasteners, and fittings, and fixtures and engines, etc., the price difference is so small a percentage of the total build as to be negligible.

Kevin

I would quite agree if I lived somewhere where marine plywood was readily available. Here I would have had to get it delivered from 200 or so kilometres away and the shipping costs would have been significant, especially if I did not order everything at once. Having said that, I would still have used marine plywood if I thought it would make a difference in the life span of the boat. But I really could not understand the need once the wood is fully protected by the fiberglass cloth and several coats of epoxy, as long as I make sure I regularly inspect the hull for any damage to the surface, which is something I always do anyway since the boat is only in the water when I use it.

Maurice

Dirc
02-04-2017, 09:23 PM
If you dry sail it always, and don't leave it in the water, I imagine the life could be fairly extended.

The consensus on regular ply is that the voids are what get it in the end... mostly a matter of time and moisture
Even fully fibre-glassed inside and out, condensation into the voids will cause it to rot from the inside out.

use your knuckle or instrument to check all over for mushyness
you may have been lucky and had minimal voids, I hope so, it's a cute little thing

mau_ben
02-04-2017, 10:00 PM
If you dry sail it always, and don't leave it in the water, I imagine the life could be fairly extended.

The consensus on regular ply is that the voids are what get it in the end... mostly a matter of time and moisture
Even with fully fibre-glassed inside and out, condensation into the voids will cause it to rot from the inside out.



Well, I'm 72 so there is a good chance that it will either outlive me or I'll get rid of it while I still have my sanity BY:D
I did use outdoor plywood though and not regular plywood, so in theory, that should help. At any rate, I have no intention of going down with my ship :d This is just a fun boat and if it dies, it dies. Most of the pleasure I get from it is the reaction I get from people seeing it. It brings on lots of smiles, especially from kids. At the Midland TugFest, they were lining up to get their picture taken inside the boat. The only 'problem' with all the attention is that I have to allow an extra half hour to talk to people when I launch and when I retrieve the boat |:)

Maurice

mau_ben
02-04-2017, 10:42 PM
The consensus on regular ply is that the voids are what get it in the end... mostly a matter of time and moisture
Even fully fibre-glassed inside and out, condensation into the voids will cause it to rot from the inside out.



Just one more thought regarding internal rotting. Builders don't use marine plywood on the roof of houses and the roof is subjected to much worse conditions under the shingles than a fiberglass covered hull. Even with heavy snow loads, I never heard of residential roofs collapsing because of plywood or particle board rot, even on houses that are a hundred years old. It probably happens, but very rarely I think.
All & all though, I'm sure marine plywood is a better material if durability is an important issue.

Mo 'Poxy
02-04-2017, 10:57 PM
Adorable!! I think you made a good choice, for something like your mini-tug you will likely never see a difference between 'marine' and a good grade (ACX or BCX) "exterior".


I agree. It depends on the use, desired longevity and consequence of failure.

I built my rowing scull out of flooring underlayment http://seascull.blogspot.com/2014/02/the-sea-scull-panels.html The underlayment is garbage that I would not recommend. But the boat is used on milk ponds and the FFRS and sliding seat can be used again in a future build after the underlayment rots to pulp or cracks like an egg shell.

However, for the BW, only Hydrotek BS-1088 would do.http://boatbw.blogspot.com/2014/10/meranti-and-moose.html?m=1

Jamesh
02-05-2017, 04:46 AM
I have used wisa for ply and its been fantastic. Better than the wbp exterior ply we often get. I would trust it more than any unknown wbp or bs1088 ply.
James

Oldad
02-05-2017, 10:23 AM
Another important difference is that your tug will probably never reach planing speeds and will therefore not be subject to a great deal of stress pounding through a chop. Your ply should be fine.

swoody126
02-05-2017, 10:42 AM
Maurice, i applaud your choice with regards to exterior plywood Y>

it will be fun to follow your little girl as she entertains & amazes the masses(pureists be &$%#'d)

projects like yours are what puts the bug in the minds of wannabes and knocks them off dead center to begin their own project

i am currently in the process of building 2 MINI MOUSEBOATS out of big box store materials that are intended for youth activities associated with the museum, FARLEY BOAT WORKS, in Port Aransas, Texas USA

i'm thinkin there is no stronger acid than inexperienced youngsters when it comes to put projects/materials to the ACID TEST...

together we will go forth and provide happiness wherever our boats go and for long as they last...

it would be really nice if you could join us, with your little girl, at the PLYWOODEN BOAT FESTIVAL in Port Aransas, Tx(a fir piece frum u) in mid October, 2017

sw

sailcanoefan
02-05-2017, 10:50 AM
Well I read from Glenn-L marine that construction plywood is good for boat building.....as long as it has the mention ''EXTERIOR''
Wood used to make plywood should usually be Douglas Fir

My boat, 19 ft cruising daysailer was built with this type of plywood.

I used fiberglass and epoxy for hull exterior.
Then I ''painted'' inside (Bilge and sides) with 2 coats of epoxy first and 2 coats of white epoxy paint for finish (polyurethane is good).

Most of the time, to my boat, inside or outside, wood is never wet.
I also put epoxy inside limber holes.

The big difference between marine and exterior construction plywood are the amount of layers.....while MARINE has more layers.
Marine plywood has a nicer look though, like OKUME, ready to be varnished.
Construction plywood is intended for being painted because it has a poor look.

This being said, if you want to build an OCEANIC boat that will last 100 years, use Premium Quality Marine Wood ONLY.

For a small boat that gets wet few times in a year, don't hesitate for construction exterior wood.
Because it's many many times easier to have maintenance on a small boat than a big boat.

sailcanoefan
02-05-2017, 11:01 AM
Well, I'm 72 so there is a good chance that it will either outlive me or I'll get rid of it while I still have my sanity BY:D
I did use outdoor plywood though and not regular plywood, so in theory, that should help. At any rate, I have no intention of going down with my ship :d This is just a fun boat and if it dies, it dies. Most of the pleasure I get from it is the reaction I get from people seeing it. It brings on lots of smiles, especially from kids. At the Midland TugFest, they were lining up to get their picture taken inside the boat. The only 'problem' with all the attention is that I have to allow an extra half hour to talk to people when I launch and when I retrieve the boat |:)

Maurice

Clever words Maurice!!! You are right, at 72 years old, who wants to build a personal boat that will last 100 yearsY:o
I built my 19 ft cruising sailboat at 64 years old; I used construction plywood ''Exterior'' and I enjoy sailing it, so does my wife.
People come to see this boat coming from ''another time'', designed by Mr. Bruce N Crandall in 1940.
Fortunately, today we have better materials like epoxy and fibreglass.

I tip my hat to this great job.

Sincerely,
Réal, from northern Montreal.

Dirc
02-05-2017, 11:56 AM
Just one more thought regarding internal rotting. Builders don't use marine plywood on the roof of houses and the roof is subjected to much worse conditions under the shingles than a fiberglass covered hull. Even with heavy snow loads, I never heard of residential roofs collapsing because of plywood or particle board rot, even on houses that are a hundred years old. It probably happens, but very rarely I think.
All & all though, I'm sure marine plywood is a better material if durability is an important issue.


The reason ply in a roof works is because it allows the outside air to move freely and easily inside of it. This means that the ply may indeed get damp, but it dries out quickly also. Many soffits with holes & vents are used for exactly this purpose. The ply in a roof is not covered on the inside - so it can dry out quickly & won't hold moisture long.

http://diy.blogoverflow.com/files/2011/12/RoofWithSoffitRoofVentAndBaffle.png

I really like the tug you built, she looks extremely sharp and I'm sure she brings much joy to all who see her.

birlinn
02-05-2017, 02:02 PM
I had some far eastern allegedly 'WBP' ply I used for a companionway hatch.
Looked good but de-laminated in 6 months.
Beware!
Or subject a sample to a few days simmering, which is what I did with the next lot.

sailcanoefan
02-05-2017, 02:50 PM
I had some far eastern allegedly 'WBP' ply I used for a companionway hatch.
Looked good but de-laminated in 6 months.
Beware!
Or subject a sample to a few days simmering, which is what I did with the next lot.

So far my boat was ''wet'' for 4 months continuous. Nothing happened.
Only the White epoxy paint used for cabin and cockpit got a yellowish tint, not sun friendly.

I will use ''White Polyurethane'' marine paint next spring when sun will warm up in May.

mau_ben
02-05-2017, 03:34 PM
The reason ply in a roof works is because it allows the outside air to move freely and easily inside of it. This means that the ply may indeed get damp, but it dries out quickly also. Many soffits with holes & vents are used for exactly this purpose. The ply in a roof is not covered on the inside - so it can dry out quickly & won't hold moisture long.

.

Good point. Since both sides of my plywood are epoxied, any moisture is indeed trapped inside. But I'm pretty sure the wood I used was quite dry. I had to make a wide scarf to join 2 sheets of plywood and I don't recall seeing big voids or dampness. But as I said, this is a moot point for me anyway. I wasn't trying to convince anyone not to use marine plywood |:)

Thanks for the nice words.

Maurice

mau_ben
02-05-2017, 03:46 PM
Maurice, i applaud your choice with regards to exterior plywood Y>

it would be really nice if you could join us, with your little girl, at the PLYWOODEN BOAT FESTIVAL in Port Aransas, Tx(a fir piece frum u) in mid October, 2017

sw

i would love to be there if I could teleport to Texas. But I fear that the 3,000 km drive towing a trailer is more than I or the boat can handle |:)
But thanks for the invite anyway. It would be fun.

mau_ben
02-05-2017, 03:56 PM
Another important difference is that your tug will probably never reach planing speeds and will therefore not be subject to a great deal of stress pounding through a chop. Your ply should be fine.

Huh...not quite right there. I can reach 32 km/hr and the boat reaches planing speed at about 20 km/hr. It has taken a severe beating a couple of times when I crossed some big wakes but most of the time, I only take it out when the water is fairly calm and also, I'm really seldom in a hurry, so I just like to cruise slowly and gawk at the beautiful scenery and expensive cottages in this area. That is why I built that boat |:)

Maurice

mau_ben
02-05-2017, 04:02 PM
Thank you Réal. Based on what the weather has been lately, I think it may be a while before either of us goes boating again. |:)

Maurice

sailcanoefan
02-05-2017, 04:26 PM
Thank you Réal. Based on what the weather has been lately, I think it may be a while before either of us goes boating again. |:)

Maurice

Yep!!! We should think about a horse and an open plywood sleigh !!!

Mo 'Poxy
02-06-2017, 12:17 AM
2 coats of white epoxy paint for finish (polyurethane is good).

The big difference between marine and exterior construction plywood are the amount of layers

Most "epoxy" paints, like Rust-Oleum Appliance Epoxy and Pettit EasyPoxy are misnamed and are not epoxy. I have used them both, really like them both and will use them again. But, they are not epoxy.

Number of layers is one aspect that makes marine ply superior. No internal voids and alternating ply thickness (for different bending characteristics depending on bending direction) are also important factors.

Be leary of labels. I saw some plywood at Lowes labelled "Marine Plywood." It was 7-ply 3/4-inch. 3/4-inch marine should be 13 plies. Seven ply 3/4-inch is the garbage that I once used to build an outhouse

Oldad
02-06-2017, 09:24 AM
Huh...not quite right there. I can reach 32 km/hr and the boat reaches planing speed at about 20 km/hr. It has taken a severe beating a couple of times when I crossed some big wakes but most of the time, I only take it out when the water is fairly calm and also, I'm really seldom in a hurry, so I just like to cruise slowly and gawk at the beautiful scenery and expensive cottages in this area. That is why I built that boat |:)

Maurice

32 km in that boat? You are a brave man, Maurice. I am sure it was not designed for those speeds.
What do you have for power?
I think "cruise slowly and gawking" is a better use of your very pretty little boat.

sailcanoefan
02-06-2017, 11:05 AM
Most "epoxy" paints, like Rust-Oleum Appliance Epoxy and Pettit EasyPoxy are misnamed and are not epoxy. I have used them both, really like them both and will use them again. But, they are not epoxy.

Number of layers is one aspect that makes marine ply superior. No internal voids and alternating ply thickness (for different bending characteristics depending on bending direction) are also important factors.


Who said I used Rust-Oleum or Pettit Easy epoxy???
I used ratio 3:1 epoxy paint sold here in Canada exclusively made by ''Les Produits Chimiques Citadel'' or ''Citadel Chemicals Co.'' a local company
(and this paint is definitely epoxy).
Pettit paints are available in Canada, but I'm not sure about Rust Oleum.

I knew that the paint I used was not sun friendly, but I used it to have a thicker protection in addition to original epoxy and fibreglass.
Next paint, I will use Interlux polyurethane (sun friendly).

Concerning plywood, I know marine plywood is better choice.
And again, before using construction BC fir exterior plywood for building my boat, by surfing the net WEB I ended up on Glenn-L marine where they mentioned ''EXTERIOR'' plywood is a good choice. They also say that ''MARINE'' is better.

Many people used good construction plywood and built a good boat.

Maintenance to a small boat is always much easier than a big one.

mau_ben
02-06-2017, 09:44 PM
32 km in that boat? You are a brave man, Maurice. I am sure it was not designed for those speeds.
What do you have for power?
I think "cruise slowly and gawking" is a better use of your very pretty little boat.

Actually, the boat was designed for 10-30 Hp. Mine is 20hp and unless the lake is very choppy, it handles quite well at that speed, but as I said, most of the time, I just putter around |;)

sailcanoefan
02-06-2017, 11:01 PM
Actually, the boat was designed for 10-30 Hp. Mine is 20hp and unless the lake is very choppy, it handles quite well at that speed, but as I said, most of the time, I just putter around |;)

I went to Montreal's boat show last friday......Pfeeeeewwww

I saw one pontoon boat pushed by 2 Yamaha 300 HP engines!!! Sure the guy won't just putter around !!!!

I think you're right Maurice, and I enjoy sailing my boat at 4 knots on fair wind - or motoring with my small new 2.5 Hp Yamaha !!!
It runs for 2 hours at half throttle burning 900 ml of super gasoline = $0.50 an hour !!!!

Dan McCosh
02-07-2017, 11:29 AM
The main problem with exterior plywood isn't the durability, but the quality of the veneers. It often has knots, voids, an inferior finish, etc. It usually isn't too difficult to select a couple of good sheets, which would work fine for a boat.

Simonas
02-25-2017, 02:40 PM
Maurice,
very nice job.
Do You have an idea how many hours have You spend on it?
Plans says 180 hours (6-8weeks) for Candu Jr. That seems odd for me.

mau_ben
02-26-2017, 12:15 AM
Maurice,
very nice job.
Do You have an idea how many hours have You spend on it?
Plans says 180 hours (6-8weeks) for Candu Jr. That seems odd for me.

Wishful thinking for sure. I completed mine in 10 months, but I was working practically full time since I am retired. I started logging my hours at the beginning but I gave up counting after about 200 hours. By then, I was barely started, probably around 20 % done.

Having said that, I know some people who claim they completed the same boat in about 3 months. I guess it depends on your skills and how fast you work. I started in late July and by November, the basic structure was done, but the finishing part took much, much longer than I expected. That includes motor, controls, instruments, fiberglassing some of the exterior surfaces, sanding, painting, sanding, painting...ad nauseum. I made several cosmetic improvements which added many hours of labour and I made some mistakes as well which caused me much grief since I had to redo some parts.

Bottom line, ignore what they say about building time. Too many variables to predict how long it will take you. You need basic woodworking skills and some more advanced ones like scarfing sheets of plywood and you should read as much as you can about fiberglassing and/or watch videos if you are not already familiar with fiberglass.

Anyway, hope I answered your question somewhat |:)

Maurice

Simonas
02-26-2017, 03:01 PM
Maurice, that's what I though. :) Do You have any idea, why Candu Ez is estimated almost triple time comparing to Jr.?

Phil Y
02-26-2017, 05:01 PM
Nice job. Marine ply rots too. The trick is to not let water in, particularly at fasteners and fittings, any protrusion really. If you are pounding over wakes, check for hairline cracks along the keel and chines, inside as much as out. If the boat spends most of its life out of the water and under cover it will certainly outlive you.

mau_ben
02-26-2017, 05:12 PM
Maurice, that's what I though. :) Do You have any idea, why Candu Ez is estimated almost triple time comparing to Jr.?

Hard to say for sure besides the fact that it is much bigger than the Jr. In some ways I think it may be somewhat simpler since it has a flat bottom, but the wheelhouse is much bigger, so more work there.


Anyway, I don't really see why it should take 3 times as long. I'm quite sure that I would have been able to build it in twice the time it took me for the Jr, but that's just a guess since I did not see the plans. I think fewer Jr's have been built compared to the EZ, based on the pictures I have seen on the web. The "Perfect 10" should be a quicker build since the aft hull is much less complicated to build.


One thing to keep in mind with the EZ is that it will not plane as far as I know. It is a displacement hull, so you will be cruising at a much slower speed (if that matters to you).

Cheers,
Maurice

mau_ben
02-26-2017, 05:27 PM
Nice job. Marine ply rots too. The trick is to not let water in, particularly at fasteners and fittings, any protrusion really. If you are pounding over wakes, check for hairline cracks along the keel and chines, inside as much as out. If the boat spends most of its life out of the water and under cover it will certainly outlive you.

I quite agree. Inspection of the hull is key to longevity. I had the boat in a marina for a few days and one corner of the rearmost part of the floor had been rubbing against the dock and the fiberglass had worn out and water got in. I had to repair it by cutting & rounding the corner and adding rubber 'bumpers' to protect the corner.


After that experience, I decided that leaving the boat in the marina was not a good idea, so it sits at home now when not in use. Also, the boat takes quite a bit of pounding at times with tremendous noise, so I'm almost anal with the inspections as I wonder sometimes if it is going to fall apart. So far so good though :D


Maurice

mirrordude
02-27-2017, 11:23 AM
Maurice, very nice job.
Do You have an idea how many hours have You spend on it?
Plans says 180 hours (6-8weeks) for Candu Jr. That seems odd for me.


I'm about 2/3 in to my build of the same boat:

http://forum.woodenboat.com/showthread.php?209810-First-time-builder-Candu-Junior-Mini-Tugboat

and I've got about 200 hours in, which includes all of my preliminary reading of the Gougeon book, etc. I did use a CNC machine which cut some labor out, but I've got no doubt an experienced builder that is already familiar with epoxy work could build one of these in two months full time.

mau_ben
02-27-2017, 02:35 PM
I'm about 2/3 in to my build of the same boat:

I did use a CNC machine which cut some labor out, .

I would say this is a bit of understatement. I don't know exactly how many hours I spent laying out all the measurements and then making most of the cuts with a jigsaw, but I'm quite sure it exceeded 200 hours. I know I am slow, but believe me, do not underestimate the labor required just to cut all the parts if done by hand. Just saying :) .

mau_ben
02-27-2017, 04:52 PM
Maurice, that's what I though. :) Do You have any idea, why Candu Ez is estimated almost triple time comparing to Jr.?


One more thing about the Candu Ez. Here is a video showing some of the construction steps. That should give you a better idea about the labour involved


https://youtu.be/TBZoihvwacw

mermod
02-28-2017, 06:43 AM
I don't know what on earth that boat is in the video but I can assure you it is not a Candu

Phill

mau_ben
02-28-2017, 08:44 AM
I don't know what on earth that boat is in the video but I can assure you it is not a Candu

Phill

it could be a modified Candu. Many builders, including myself have made some non structural modifications. Anyway, looks like a modified Candu to me (mostly wheelhouse modifications), but I could be wrong. If it's not, it certainly is inspired by the Candu |:)

mermod
02-28-2017, 03:43 PM
possibly a guy that once glanced at a Candu on a dark night :)

Phill

mau_ben
02-28-2017, 05:22 PM
possibly a guy that once glanced at a Candu on a dark night :)

Phill

Well, you do have to be a bit creative and crazy to build a boat :D

Simonas
03-01-2017, 02:19 AM
In description it says "without plans". :)

mau_ben
03-01-2017, 09:52 AM
In description it says "without plans". :)

i should have read that first |;). I still think he took his inspiration from the Candu because it still looks like one to me. Very skilled guy though to figure out how to build this without plans. I doubt he was a first time builder but who knows? Just because I couldn't have done it means nothing really :)