GV10 Stop and Start Project

[MikeyGnz]

Got most of the way through welding up the next frame then my welder died. The repairman is on holiday until 19 Jan so no progress expected until then.

[Fuzz]

Got most of the way through welding up the next frame then my welder died. The repairman is on holiday until 19 Jan so no progress expected until then.

Dang the luck Oh well we will be waiting for updates when they can happen

[MikeyGnz]

Still waiting on welder repair but just asked a question about the reinforcing/strakes I am planning to the bottom of the hull. See https://forums.bateau2.com/viewtopic.php?f=1&t=63878 for my question.

I will copy the question and answer here once I have a reply so all of my build is in the one place.

[MikeyGnz]

Hi, I have a completed Gv10 in Christchurch. Would love to see yours when done if you don't mind?
Cheers
Pete

Hi Pete

Had my bosses boss come see me the other week, turns out he is a friend of yours and knows your boat/build.

[peterrivers]

Yep he said, small world!

[MikeyGnz]

Ok so here is a copy of the question I posted in the 'plans and building' section:

Hi

The Hull Assembly A plan for the GV10 shows a pair of 2 by 4s screwed to the bottom of the hull to keep the panels flat during assembly. I was thinking to permanently mount 40x40x3mm alloy angle to give added stiffening to the bottom panels and form strakes on the final hull.

How far forward from the transom should I go with these, that is how long is the flat section of the hull bottom?

Would these strakes on the outside be worth it or should I install them on the inside of the hull so I have reinforcement without the strakes?

Thanks

Mike

And responses I got from Evan and other builders.

From Fair WX Pilot

Hi, this is all based on my standard construction. As your building from aluminum you probably want to wait for a response from Jacques or Evan Gatehouse as he designed the original.

The hull is completely flat from Frame 2 aft to the transom. I found that the 2x4's really helped keep everything flat and prevent rocker as you bend the panels up to the front. Once the bottom stiffeners and transom gussets were installed it was all very solid. When doing similar on 6061 aircraft skins I sometimes place temporary stringers on the outside picking up on the rivet holes I plan to use once I am ready for the internal stringers to go in.

Though I haven't been to full "hold my beer" speed in my GV10, I have had it well on the way and mine shows no sign of slipping in turns or doing anything nasty. In fact it seems to turn on a sixpence. If the strakes have to be there for structural reasons due your build changes then that's the answer but functionally it all seems to work very well without them.

As I said above, please check with the designer as your build may not be comparable to mine due the material. Enjoying watching it all come together and looking forward to more pictures.

Thanks Alan. I read your OD18 thread in one sitting last night. Impeccable work there. Seeing the amount of fairing and sanding you had really makes me appreciate alloy but worries me as well as I cannot fair out any hook or rocker that others have run into.

From peterrivers

Hi Mike, I formed the stiffners by glassing over half a waterpipe foam insulation tube... To make it easier on the feet.

I would also keep the outside of the hull clean, is no strakes. Its handling is great as designed, and I have had it flat out with one pob and 15hp.

Cheers

Maybe cut a length of 2" aluminum tube in half and weld that in? Will need to be bent to the hull shape.
Alternative maybe a length of 1" square? Either would be fine on the feet...

Thanks Peter. Your GV10 looks very nice in the photos. Nice Surtees as well. I've got access to my dads 6m McLay at the moment if you want a second boat along to go further out.

The pipe approach sounds real good. It will depend on how stiff the final hull is, I'm half making this up as I go but if extra stiffening is needed I will put reinforcement in after the frames so could do half pipe sections in the flat areas and the curved stringers from the plans forward. I will check what extrusions I can get off the shelf as well, maybe I can avoid the lengthwise cutting.

I'm also considering 1 inch pipe all around the top of the side panels, bow panel and transom (except motor clamping area) but will wait until hull is fully welded to see how stiff it is.

And from Evan Gatehouse

Yes, it's really hard to get external strakes right and not mess with handling. The internal stiffeners formed with glass over foam half pipes is pretty gentle on the feet.

Our GV10, with an aged 15 HP motor and 1 person, topped out around 26 knots. It's pretty quick at full throttle. With 1 person, and high speeds take it easy in turns. Such a short hull can wash out and "spin out", putting a lot of side load on passengers.

Thanks Evan. I'm enjoying the build so far and looks like I should end up with a good durable boat.



I have read about others having issues with hook or rocker on their build so was thinking that welding strakes/reinforcing on the bottom panels prior to fitting them to the hull might help avoid it. Going on the advice from everyone I'm not going to add strakes and will add internal hull reinforcement as required.

I've got to say it is great to have a forum like this to be able to throw ideas and questions.

[pee wee]

One of the things that contribute to a hook at the transom is multiple fiberglass tape layers, requiring lots of fairing compound to make it flat again-you won't have to deal with that.

[fallguy1000]

Been a day since the repairman got back and no updates!

More seriously, what is this gonna weigh in ally?

Also, I don't weld, but it sure is fun to watch this project.

[MikeyGnz]

Been a day since the repairman got back and no updates!

More seriously, what is this gonna weigh in ally?

Also, I don't weld, but it sure is fun to watch this project.

His first day back was a Saturday and they only work a half day on Saturdays. I decided to give him that to catch up and will be calling when they open today.

Density of aluminium is 3 times that of plywood but since I am using 2.5mm alloy instead of 6mm and 10mm and no epoxy, fairing compound or paint I'm expecting roughly the same weight hull as on the plans.

I'm building this partly as an experiment to test my welding before I buy a jet-boat kitset and am pretty much taking a guess at thicknesses, reinforcement, etc. so hopefully I end up with something that works.

[fallguy1000]

Been a day since the repairman got back and no updates!

More seriously, what is this gonna weigh in ally?

Also, I don't weld, but it sure is fun to watch this project.

His first day back was a Saturday and they only work a half day on Saturdays. I decided to give him that to catch up and will be calling when they open today.

Density of aluminium is 3 times that of plywood but since I am using 2.5mm alloy instead of 6mm and 10mm and no epoxy, fairing compound or paint I'm expecting roughly the same weight hull as on the plans.

I'm building this partly as an experiment to test my welding before I buy a jet-boat kitset and am pretty much taking a guess at thicknesses, reinforcement, etc. so hopefully I end up with something that works.

Very cool! I was totally joking about the repairman.

Good luck. Love the work and watching the welds improve. Do you know what a mousehole is?

When you weld a boat, no weld is allowed at intersections of three planes. Instead a relief hole is cut on the transverse framing. Aka mousehole.