PM38 Build Log.
Posted: Thu Apr 07, 2016 2:32 pm
Hello folks,
This is a build log of my first boat. I have been looking around and decided the PM38 would be an easy enough boat to tackle and be functional at the same time.
The goals of this boat are:
1. To be lightweight so that my SO and I can easily launch and retrieve the boat.
2. To be light enough to allow my 240sx to tow it so trailer and boat must weigh < 800lbs with less than 200lbs straight on the hitch.
3. Be fast enough to allow transport around a lake > 25mph
4. Be simple enough and robust enough that I can build it with horrid wood skills.
Seems the the PM38 matched all, well I mean most, of those.
Image 1:
A few days into the build I had built the frames #2 and #4 and confirmed with myself that I was capable of constructing square and rigid shapes.
This was my mental sanity check. If I could not build these frames I was going to stop while I was only ~100$ into things. Sadly I constructed them with less than 1/32" variance.
The Keelson, Transom, and Bent bit (unknown) at the front were glued and screwed together and brought into the garage.
Image 2:
Attaching the frames to the keelson was a difficult process, I spent almost an entire day moving things slightly and re-clamping. But I got everything straight and level as I could.
The frames were glued and screwed into the keelson. Here is where I noticed that the 2x4 I had selected for the keelson had a knot in it ~1/3 from the transom forward.
I have yet to fix this but I am planning on taking some 1/2" ply and screwing it to the sides like where the keelson and the Bent bit (unknown name) connect at the front just for safety sake.
Image 3:
Up until this point I have still been very unsure of the rigidity of the whole project. Too much weight anywhere and the whole frame would walk and have to be re-aligned.
But as I started adding the bottom battens I was impressed by the quick gains in rigidity throughout the entire frame.
Some mistakes were made. I was unsure the size of my battens as I have been buying wood on a day per day basis. When I built the transom out I was unable to cut the notches into it for the battens to sit.
I was able to use my jigsaw and a flat head screwdriver to notch out places for the chine logs but bent and broke 4 blades in the process. I didnt want to continue doing that and just screwed them flush into the transom.
The strength of them in this configuration worried me. I added 1/4" ply to each batten that lapped up onto the bottom of the transom by 1 1/2" and glued it all together. I believe the strength is okay here.
Some issues I also ran into. I am having a difficult time sourcing lumber in lengths > 12 feet that are knot free. The plans call for 16" lengths for the chine logs.
I took a 10' and a 8' length and cut at a wide angle to create a joint 6-10" long and let them dry overnight.
Image 4:
The first goal was to bend the chine logs into the bent front section (unknown name). As I was doing this I used a soaked towel and a iron to steam the wood into shape. As I was working on gluing and screwing the end in my joint snapped!
I removed both of the chine logs, sanded down where the glue was, cut out backing plates from the 2x1" material that extended > 4" on each side of the joint. Glued and clamped those together waited 24 hours re-attached the chine logs.
This time around I was very slow and spent 15-20 minutes per log with the towel and steam making sure it was penetrated well and it became quite flexable. I was able to glue and screw the chine logs into the front of the boat.
While that was gluing I cut out the bottom of the boat from 1/2" ply. The plans call for 3/8ths but it was not readily avaliable in my area. With the odd issues with the transom and battens and the keelson knot I figued id rather go larger than spec than below.
Now the frame is very rigid, I could actually imagine standing in the boat without breaking it.
Image 5:
Continued planking the bottom of the hull. With 1/4 ply. This actually has me a bit worried. I was able to get them to flex into position no cracking or major issues but when its glued down there is a bit of flex in the center of the ply.
The future plans have frame #1 going in the middle there but it generally only supports the sides. I know not much weight will ever be up there in the hull but I dont want to hit a huge wave at the right angle and have the wood snap.
I am still debating creating a lower beam out of some extra 1x4" wood to re-enfoce that plywood in place with frame #1.
The next large process was continuing the planking with the sides. The but joint lays up right behind frame #2 by about 6" where the flex from the shape is the least. It has 1/4" plywood 4" wide backing it. Waited for the glue to dry before fitting and making final trimming adjustments.
The sides have been glued onto the frame and screwed down.
I am waiting on the fiberglass + epoxy.
The plan forward is to work on frames #1 and #3, I can get them in the boat and then flip it back over whenever the epoxy shows up.
Major Worries!
1. I ordered 1.3oz fiberglass weave, enough to cover the seams + the entire underside of the hull up to the spray rails. Is this too thin? I have never worked with fiberglass before. The plans dont call for it structually. But I would feel more safe with a bit more rigidity especially on the 1/4" ply sections under the nose.
2. The knot in the keelson. Will screwing and gluing 1/2" plywood be enough to make this not break. The engine will I assume be putting a lot of stress on that area of the construction.
3. Size of the engine. I am looking in the 25hp range right now and hope that it will be enough to go ~30mph with me 200lbs + 120lbs So + 50lbs of stuff?
4. Will it float.
This is a build log of my first boat. I have been looking around and decided the PM38 would be an easy enough boat to tackle and be functional at the same time.
The goals of this boat are:
1. To be lightweight so that my SO and I can easily launch and retrieve the boat.
2. To be light enough to allow my 240sx to tow it so trailer and boat must weigh < 800lbs with less than 200lbs straight on the hitch.
3. Be fast enough to allow transport around a lake > 25mph
4. Be simple enough and robust enough that I can build it with horrid wood skills.
Seems the the PM38 matched all, well I mean most, of those.
Image 1:
A few days into the build I had built the frames #2 and #4 and confirmed with myself that I was capable of constructing square and rigid shapes.
This was my mental sanity check. If I could not build these frames I was going to stop while I was only ~100$ into things. Sadly I constructed them with less than 1/32" variance.
The Keelson, Transom, and Bent bit (unknown) at the front were glued and screwed together and brought into the garage.
Image 2:
Attaching the frames to the keelson was a difficult process, I spent almost an entire day moving things slightly and re-clamping. But I got everything straight and level as I could.
The frames were glued and screwed into the keelson. Here is where I noticed that the 2x4 I had selected for the keelson had a knot in it ~1/3 from the transom forward.
I have yet to fix this but I am planning on taking some 1/2" ply and screwing it to the sides like where the keelson and the Bent bit (unknown name) connect at the front just for safety sake.
Image 3:
Up until this point I have still been very unsure of the rigidity of the whole project. Too much weight anywhere and the whole frame would walk and have to be re-aligned.
But as I started adding the bottom battens I was impressed by the quick gains in rigidity throughout the entire frame.
Some mistakes were made. I was unsure the size of my battens as I have been buying wood on a day per day basis. When I built the transom out I was unable to cut the notches into it for the battens to sit.
I was able to use my jigsaw and a flat head screwdriver to notch out places for the chine logs but bent and broke 4 blades in the process. I didnt want to continue doing that and just screwed them flush into the transom.
The strength of them in this configuration worried me. I added 1/4" ply to each batten that lapped up onto the bottom of the transom by 1 1/2" and glued it all together. I believe the strength is okay here.
Some issues I also ran into. I am having a difficult time sourcing lumber in lengths > 12 feet that are knot free. The plans call for 16" lengths for the chine logs.
I took a 10' and a 8' length and cut at a wide angle to create a joint 6-10" long and let them dry overnight.
Image 4:
The first goal was to bend the chine logs into the bent front section (unknown name). As I was doing this I used a soaked towel and a iron to steam the wood into shape. As I was working on gluing and screwing the end in my joint snapped!
I removed both of the chine logs, sanded down where the glue was, cut out backing plates from the 2x1" material that extended > 4" on each side of the joint. Glued and clamped those together waited 24 hours re-attached the chine logs.
This time around I was very slow and spent 15-20 minutes per log with the towel and steam making sure it was penetrated well and it became quite flexable. I was able to glue and screw the chine logs into the front of the boat.
While that was gluing I cut out the bottom of the boat from 1/2" ply. The plans call for 3/8ths but it was not readily avaliable in my area. With the odd issues with the transom and battens and the keelson knot I figued id rather go larger than spec than below.
Now the frame is very rigid, I could actually imagine standing in the boat without breaking it.
Image 5:
Continued planking the bottom of the hull. With 1/4 ply. This actually has me a bit worried. I was able to get them to flex into position no cracking or major issues but when its glued down there is a bit of flex in the center of the ply.
The future plans have frame #1 going in the middle there but it generally only supports the sides. I know not much weight will ever be up there in the hull but I dont want to hit a huge wave at the right angle and have the wood snap.
I am still debating creating a lower beam out of some extra 1x4" wood to re-enfoce that plywood in place with frame #1.
The next large process was continuing the planking with the sides. The but joint lays up right behind frame #2 by about 6" where the flex from the shape is the least. It has 1/4" plywood 4" wide backing it. Waited for the glue to dry before fitting and making final trimming adjustments.
The sides have been glued onto the frame and screwed down.
I am waiting on the fiberglass + epoxy.
The plan forward is to work on frames #1 and #3, I can get them in the boat and then flip it back over whenever the epoxy shows up.
Major Worries!
1. I ordered 1.3oz fiberglass weave, enough to cover the seams + the entire underside of the hull up to the spray rails. Is this too thin? I have never worked with fiberglass before. The plans dont call for it structually. But I would feel more safe with a bit more rigidity especially on the 1/4" ply sections under the nose.
2. The knot in the keelson. Will screwing and gluing 1/2" plywood be enough to make this not break. The engine will I assume be putting a lot of stress on that area of the construction.
3. Size of the engine. I am looking in the 25hp range right now and hope that it will be enough to go ~30mph with me 200lbs + 120lbs So + 50lbs of stuff?
4. Will it float.