Building the Raptor

Which has to be determined empirically which requires it to be not raining and me to be not working and some daylight, which is a relatively uncommon confluence these days.

I know I want the CoA (Center of ***) to be just aft of the CoG and I also know that being off a few inches isn't going to make a bit of difference. It's an approximation at best.

@Milehog: I want to try a Greenland paddle before I commit to making one, but haven't had the opportunity yet. if and when I do I will probably make a laminate to give it some personality.

 

Milehog - can you give more description as to why the Greenland paddle works better? I keep looking at them and can't bring myself to believe, there is no one around here that I know with one.

Marc

 

I don't know if you can declare either a good Greenland or a fine carbon fiber paddle best for recreational paddling. They are different, in good ways, The Greenland has low impact and windage. When you hold the loom (shaft), your hands automatically position the blades at the optimum angle to the water for power and flutter resistance. The Greenland is held lower and uses a somewhat faster cadence.
By all means beg, borrow or build one. Cedar 2X4s aren't expensive.
Chances are you'll like it, if not use it as a spare.

 

If you can manage it in any way, a float test will prove highly productive. A 2" difference in my CoA made the differnce between floating on the lines or having a trim error. It's also a bit exciting to get your creation in the water and evaluate it's handling charateristics. Changes/corrections are easier to make while you're still in build mode and geared for construction. It was easy to move the clamped in place seat to a new position to check for trim errors. 2 pennies.:idea:

Progress is .

 

I guess the point is that the Centre of *** may not be be near the COG - its got to be on the Centre of Bouyancy. that is - where you can put your ***, legs and arms and it will float on its lines. This may or may not be the centre of 'dry' balance, and usually is not. Rule of thumb is - the Centre of BOuyamcy has to be under you stomach, to allow for leg weight, and the torso leaning forward to paddle.

For a kayak - you can get yourself some haybales or similar cheap, large objects, make a 20'x 3' x 2' 'swimming pool' by draping some black plastic over them and filling it with water. If you get a sandbag of significant weight, you can find the Centre of Bouyancy with a bit of adjustment.

I have built a kayak to find that I put the bulkheads too far aft, and couldn't put my *** and legs far enough forward to get trimmed. Bummer !!!

 

Ha!!!

You said, "Bum"mer.

 

Finished glassing the inside today. I did most of it the other night, but ran out of resin 2/3 of the way thought and had to get more. This left a separated zone which will probably have to be ground off and replaced. but that's not the end of the world. Either tonight or tomorrow I'll cut the bulkheads that are not dependent on COB and hopefully can get it wet on Saturday.

One lesson learned is that the less time you take on fairing and smoothing the inside, the more resin you will have to pour to wet out the cloth. I did a pretty half-assed job on the inside and it's taken over twice as much resin as a result.

The two remaining major projects are the deck and the cockpit ring, both of which I have a fairly good idea how I'm going to do. The deck should go pretty quickly and the cockpit ring, while slow, is something I've done before on the Re-YAK-tion. part of me wants to do some sort of decoration or inlay on the deck, and the other part of me just wants to get it done and worry about the fancy stuff on the next boat.

 

More progress!

I got the bulkheads cut out and at least tacked into place. Once the resin sets I'll go through with filleting compound and reinforce the joints. I hadn't realized how much the hull spread when it came off the strongback and so the blue straps are holding it in the correct shape while the epoxy sets on the bulkheads. Due to the amount of spreading force being exerted by the hull I need to make the hull to bulkhead joints stronger than I had originally anticipated. The fact that the filleting compound needs to be in and completely dry before I can take the straps off to put it in the water means we're not going paddling tomorrow. Slight delay, no big deal.

If I do the filleting tomorrow it can dry Sunday and Monday and maybe Tuesday, but probably Thursday, it can get wet.

 

I got the bulkheads reinforced today and cut the pieces that will go inside the gunwales to support the deck. I also cut out what I could of the delaminated area with a utility knife and will go back with the sander later and grind the rest out. The area that needs work is in the middle of the aft storage compartment and so it doesn't HAVE to be done right away. The filleting compound takes about 36 hours to fully cure at the temps in the shop, so probably can't do much until Tuesday anyway.

 

Got some more done on the Raptor in the last few days. The First picture shows what I'm calling the cockpit arch which is the highest point of the forward deck. I made a wooden template of the shape I needed and then went to Hardwoods to Get and asked for something super strong and big enough to cut the shape out of. $18 later I had a big slab of ash don't have to worry about it breaking. Ever.

While I was there I also got some offcuts of maple veneer from a now defunct company that made hockey sticks. I'll use these to form the cockpit ring from. I'm cutting them to 1 1/2" and laminating the ring up on a form.

I also attached the strips inside the gunwales that the deck will mate to. The purpose of these is mostly adding space for the deck to attach to. They also reinforce the bulkheads and stiffen the hull. I can't put the last ones in until I figure out where the last bulkhead needs to go.

The plan is to put her in the water tomorrow to determine COB and COA, and then the final bulkhead can go in tomorrow night.

The final picture is of the section I cut and ground out and replaced . Looks pretty good if I do say so myself.

 

Good to see the progress.

The maple veneer is quite the coup. Looks like it will be a nice strong cockpit ring. It also looks like your managing some flare on the sides of the ring. Very efficient on the use of materials.

 

IT FLOATS!

With the help of a friend (who is also my fire chief and so could launch the rescue boat if things went horribly pear shaped) she went in the water for the first time this afternoon. Stability is good and COA is right about where I thought it would be. She tracks straight and is faster than anything I've paddled before. Scott said from watching he didn't think I even got it up to hull speed. Without the bulkhead at the rear of the cockpit to act as a back rest it was pretty uncomfortable, but that will change soon. We're estimating the weight at 45-50 lbs.

So basically, I'm freakin thrilled! So far she's everything I had hoped she would be. My only complaint is that she turns like a big boat, which is to be expected from a 17' 4" hull. I had hoped by concentrating the displacement in the center I could achieve a better turning radius.

@ LP: the flare is mostly from thin veneer and heavy clamps and should come out once I start gluing things together. once I have about 3/8 to 1/2 on the ring I will start using pieces that are only 3/4" wide creating a lip for the spray skirt to grab on to.

Ideally I would like to "dish" the ring some (i.e. make it concave in the vertical plane), but I haven't figured out how to accomplish that yet. either I'll figure it out or else leave that problem for the next boat.

 

Progress continues...

I got the inspection hatches put in the fore and aft bulkheads and cut the aft cockpit bulkhead today. The hatches are 4" ABS plumbing fittings installed with 3M 5200 since I couldn't think of anything else that would stick to both resin and ABS. I didn't do the best job in the world cutting the holes, but the alternative was to spent $40 on a 5" hole saw and these aren't really appearance parts. I did discover that the plywood is stronger than I gave it credit for and even with the holes drilled around the periphery it still didn't want to pop out. I'll have to do some cleanup with filleting compound, but the hatches are basically done.

The aft cockpit bulkhead is cut but not yet installed. The clamps are holding the bulkhead to a piece of scrap 1x4 while the glue sets. Once that's done I'll paint it with resin and stick it into the boat. Probably Tuesday I'll get the restr of the pieces that need to go in before the decks go on attached and can start in on the decks Thursday.

 

Cthippo,

I am amazed at how much you get done. My kayak build is 5 months old I am struggling to get it done for Christmas.

Charge on!

Marc

 

Great stuff, CT. It's good to see you floating in her. I think the topless sea trials in a kayak is like the roll over in a larger boat. Glad to hear she paddles nicely.

It's looks like she's trimmed better in the second profile shot (leaning forward) than in the first profile.

It's very satisfying to take a design from thought to existence and all of the steps in between.