Thread: Building a speed boat

Howdy Steve,

Your location is listed as "aaaaa" - I don't know what wood you grow there!

But sometimes it can be unrealistic to stick to timber only available in one area. For example Australia is well endowed with colourful hardwood species, but many are too heavy for lightweight boats like you have chosen.

In Australia we have very nice Hoop Pine plantation plywood. But is is a smaller sheet than the rest of the world .. his may not matter with the design you have chosen, but it might be important for boats of particular sizes.

Tell us where you are and we will all try to get you along in the direction you want to go as far as possible.

MIK

Hi
If you think imported timber is dearer than local you are in for a very big shock, however, depending where you are, there are seconds ply outlets arround the country. You wont always be able to get what you want immediatly and may have to wait for the right sheets.

Thanks for the reply's

I am located in Australia Corowa near Albury

I am hoping to use Australian wood only to make sourcing wood a little easier and to avoid using imported but if imported is cheaper ill go that way

As for the weight if its near enough its good enough this is not going to be a race boat its my first attempt so if i have to fit a bigger motor thats ok

I have seen a pictures of this boat with twin 30hp motors on it and thats plenty for me even a single old 60 or 70 blueband just to get it floating
My main concern is building the boat not what engine i put on it LOL

My first purchase will be all the Timber then worry about the ply once i have it ready for it

Thanks again

This is a fairly old "puddle jumper" design and a popular one for Glen-L. It'll get up a scoot well with 30 HP. You can scare yourself with 60 HP. With 90 HP and up, you'll be in holy grail territory. An Ideal engine for good performance and reasonable economy would be a 50 HP 4 stroke. It'll weight about what a 75 HP two stroke does, but will have better mileage and low end torque for butt kicking hole shots.

"butt kicking hole shots?"

Ah ... Corowa ... know it well.

Barrels by Candlelight on Xmas Eve, the rowing club park down by the river, Newsagency and bakery on opposite sides of the main street ... perfect to start the day. Could have been the Capital of OZ of course but Sydney (my home town) kicked up a stink.

OK ... I would suggest going to the local hardware/timberyard and see what they have that glues well and about the density of Oregon.

Maybe Meranti or Hoop Pine might be available. Then get back to us. Be nice if you don't have to lug stuff back from AlburyWodonga.

See if they have any marine plywood. Though Hoop pine exterior grade ply will be fine and more likely to find so far from the sea. Like I pointed out above Hoop Plywood is 1200 x 2400 which is a bit under the 8ft x 4ft (2440 x 1220) that the boat is designed around. But if the plan has the ply layouts drawn (ie which pieces come out of what sheets of ply) you will quickly see if there is a bit of margin on the sided and edges or not.

Most Hoop Pine ply is so nicely made that even the exterior ply has nice clean faces and no voids in the interior.

MIK

Thanks again

So for the timber i should be looking for something as strong as Oregon but glues easy

Sound easy enough

Ill go today and get some prices

Another question about ply

Is it a must to use marine ply

My mate is a chippy and he told me last night that marine ply is a big ripoff
All marine ply is AA ply meaning it has a pretty surface both sides

AB ply is good 1 side average the other and the list goes down from there

Is he right or just talking from a chippy's perspective like for doors and stuff

When i mentioned it was A sheets all the way through he just laughed and said pull on apart and find out

Dont get me wrong i have no intention of using door ply for a boat unless it would work and last 10 years

Thanks agiain

Marine ply, graded under the Australian Plywood Assoc. is an F14 grade. Most exterior plywood is graded as F6 to F7 , although you can get F14 as well. Typical plywoods that you get from the hardward store etc are usually made from hardwoods and imported from Asia. These plywoods do not have an "F" grade as they are structurally to weak and made from rubbish. Beware the plywood you buy.

Unlike small yachts, power boats have far greater hull pressures and, these vary along the length of the hull( they also vary along the hull with yachts too). Using solid First Principles, the governing factors for hull pressure is LWL, displacement, width of the bottom plate, speed and angle of deadrise. Knowing these factors, you then engineer the panels to take these loads which is then based on frame spacing, stringer spacing the mechanical properties of the plywood and it's hull loading (or pressure) at that location along the hull, defection of the material and then include a safety factor. Overall this means the difference between a sound boat and a structural failure.

The problem with buying old plans or even plans from another country, is that the plans usually don't conform to Australian Builders plate compliance in regards to power boats. This then means that prior to registration, you'll need to send the plans to someone qualified to look over the design and do some number crunching for the numbers to go onto the plate. It also means being that the boat is under 19ft or 6m, you'll need bouyancy in the form of expandable foam to support the boat in either a basic or level condition. This means that the boats weight ( hull only)needs to be calculated along with the motor in order to determine the boats max capacity and number of persons allowed,which is also required for the plate. In regards to our designs, all our power boats have been calculated for the builders plate. If someone in NZ for example, builds the boat and doesn't need to furfill the requirements..fine. However if built here in Oz, the numbers are available along with the required amount of foam and location within the boat.

I'm curious, what is the frame spacing and the stringer spacing for this boat? I'm thinking probably 3ft frame spacings and 12in stringer spacings based on your boats bill of materials. Just wondering.
regards
Mark

Good on ya for having a go anyway.

There is always plenty of help from these pages anyway.

Beware of being specifically Aus with your choices of wood. Hoop pine plantation timber clears may cost up to $4000.00 a cube when imported real Mahogany will cost around $2500 a cube. The mahogany is also a far better timber for use in boats.

Austral's hoop pine marine ply is an excellent product but much denser than gaboon which is more common in US designs.

It is difficult to get through the smoke and mirrors at the start with getting plans approved.

Steve-35 is probably more confused now than before
Steve, just go and have fun building it and have a ball on the water
regards
Mark

Yes i do know this is going to be a bit more work than putting a set of carpets in a torana
But it took 30 years to work out that i had been wasting my money on cars when i should have been wasting it on boats so im gunna try and make the most of it

Its funny i went to 2 wood shops yesterday i didnt go to my local luckily

the first guy just told me straight out "thats not metric plans mate) sorry cant help you

So i went else where

2nd guy looked at me funny for a minute and then started to tell me where i had stuffed up ive wasted my money it will never float it will never get rego like its car or something

he seemed too think because the measurements are in imperial its going to be impossible to convert the plans to metric (why would i want to}

So at this point i eventually cracked the shitSSSS with the second guy

I shouldnt have but i said it

What the is wrong with you it doesnt matter what the plans are in ill just buy a bloody imperial tape measure im cutting it myself

For some reason every one wants to convert it to metric like imperial is some strange language that they have never heard of
Funny thing is its still the most widely used measuring system in the rest of the world UK USA Europe

I tried to explain it to him like this

It doesnt matter what word you use its the number that matters
6 and a quarter is 6 and a quater metric or imperial
Yes they are different size but thats not whats relevant


EG i could make my own tape measure and call them dogbums instead of cm or inches it makes no differance its still 6 dogbums no matter what you hold the tape against

I dont think he understood cause he told me flock off lol



I sent out a few emails and one guy wanted to charge me 30 bucks an hour to convert the measurements to metric and then give me a quote on the wood

Gotta luv em

Steve, it took me 30 years to figure out I couldn't afford to waste it on both cars and boats so know it's just boats It's much more fun going fast in a boat with friends than on your own for a 1/4 mile . I too found it hard to get sense out of some suppliers but also found the help and info from those around this forum to be invaluable, keep at it it will be worth it

Originally Posted by Mark Bowdidge

Marine ply, graded under the Australian Plywood Assoc. is an F14 grade. Most exterior plywood is graded as F6 to F7 , although you can get F14 as well. Typical plywoods that you get from the hardward store etc are usually made from hardwoods and imported from Asia. These plywoods do not have an "F" grade as they are structurally to weak and made from rubbish. Beware the plywood you buy.

Mostly agree, particularly ignore advice from Chippys who have not had much boat experience. It is not good advice. Basically beware anyone who says you should not do something because "it is a rip-off". It might actually be the soundest choice that can be made.

Basically, you should use marine grade ply because it has fewer interior voids than exterior or other lower grades. The exterior Hoop pine is one exception as the quaility of the veneers is so high.

Another way of filtering out rubbish is to buy from suppliers who know a lot about boats and have a track record of supporting their customers.

If I see another exterior ply I can make a judgement about whether it is suitable or not. But the above advice is the best I can give to someone that doesn't know about plywood (yet!).

Unlike small yachts, power boats have far greater hull pressures and, these vary along the length of the hull( they also vary along the hull with yachts too). Using solid First Principles, the governing factors for hull pressure is LWL, displacement, width of the bottom plate, speed and angle of deadrise. Knowing these factors, you then engineer the panels to take these loads which is then based on frame spacing, stringer spacing the mechanical properties of the plywood and it's hull loading (or pressure) at that location along the hull, defection of the material and then include a safety factor. Overall this means the difference between a sound boat and a structural failure.

All well and true ... but more complicated than need be for Steve's needs. The designer at Glen L or any other reputable designer has already made that call and taken average grade materials into consideration. The boats also have a seriously long track record.

The problem with buying old plans or even plans from another country, is that the plans usually don't conform to Australian Builders plate compliance in regards to power boats.

For a self build boat the problem is not too big usually. There are a number of discussions on this forum. Basically the creation of the plate has no basis in legislation - it only has to be present on the boat. and you can make your own. Contact the designer for any items not mentioned in the plans such as maximum number of people.
https://www.woodworkforums.com/showth...lder%27s+plate

The GlenL plans are from the USA, but the regs for buoyancy for australia are lifted from the US Coast Guard regs ... so GlenL will know about them and may be able to give useful advice.

Another good reason to get plans that are supported by the designer.

During that stage of the inspections they will ask where your builder's plate is, and if it conforms to the standard they will tick that square on the form.

Best wishes
Michael

More builder's plate and buoyancy info here

https://www.woodworkforums.com/showth...lder%27s+plate

MIK