Gentry flotation and HP calculations - Any available?

Designs for inboard or outboard power

Moderator: BruceDow

Post Reply
Trackhappy
Posts: 1412
Joined: Wed Feb 17, 2010 5:42 pm
Location: Sunshine Coast, Queensland, Australia. Building Gentry.

Gentry flotation and HP calculations - Any available?

Post by Trackhappy » Sun Jun 06, 2010 8:56 pm

In Australia an owner-built boat now has to have an "Australian Builders Plate" fitted prior to sale if it was built after 2006. I don't have any plans to sell Genry yet, but this seems to be the right time to get the information, and plan inbuilt buoyancy etc. if required. Trying to fit it in later might be difficult.

This standard explains the requirements:
http://www.nmsc.gov.au/media/pages_medi ... 0Boats.pdf

It seems that the buoyancy calcs/tests and maximum HP are the two that will be required as an owner builder for this type of vessel. If Glen-L has them, then a copy of them with a formal declaration is what I would need. Does Glen-L calculate such things or possess the necessary software for them?

Thanks.
Glenn.
By the time I have built a boat, I'll be ready to build a boat....

User avatar
BruceDow
Posts: 2132
Joined: Sat Jun 17, 2006 2:21 pm
Location: Toronto, ON, Canada
Contact:

Re: Gentry flotation and HP calculations - Any available?

Post by BruceDow » Mon Jun 07, 2010 2:57 am

To my knowledge, Glen-L does not have or supply that information.

Send a PM to Mr. Hot Rod... He wrote a very nifty spreadsheet took that helps with the calcs. It is lined up the the harmonized Canada/US regs (except for that little "metric" thing that we use). If Aus is similar, his tool may give you a great starting point. (I had a quick scan of your link, and they look similar)

You could use such a spreadsheet as "documentation" of your flotation calculations. (It looks very "official")

B.
Bruce.

~~ Do what you love, and love what you do. ~~
~~ To me - only my boat is not yet perfect. Everybody else's is to be admired for I know the path they have walked (Dave Lott, 2010) ~~
Dow's Monaco Project

Trackhappy
Posts: 1412
Joined: Wed Feb 17, 2010 5:42 pm
Location: Sunshine Coast, Queensland, Australia. Building Gentry.

Re: Gentry flotation and HP calculations - Any available?

Post by Trackhappy » Mon Jun 07, 2010 3:01 am

Its amazing really, these Guys actually expect you to sink your boat to prove this.... :shock:
By the time I have built a boat, I'll be ready to build a boat....

Trackhappy
Posts: 1412
Joined: Wed Feb 17, 2010 5:42 pm
Location: Sunshine Coast, Queensland, Australia. Building Gentry.

Re: Gentry flotation and HP calculations - Any available?

Post by Trackhappy » Mon Jun 07, 2010 3:57 am

Bruce Dow wrote:To my knowledge, Glen-L does not have or supply that information.

Send a PM to Mr. Hot Rod... He wrote a very nifty spreadsheet took that helps with the calcs. It is lined up the the harmonized Canada/US regs (except for that little "metric" thing that we use). If Aus is similar, his tool may give you a great starting point. (I had a quick scan of your link, and they look similar)

You could use such a spreadsheet as "documentation" of your flotation calculations. (It looks very "official")

B.
Thanks Bruce. I have left a PM, we are Metric here. Makes calcs easier.
By the time I have built a boat, I'll be ready to build a boat....

User avatar
Mr Hot Rod
Posts: 978
Joined: Thu Mar 03, 2005 2:40 pm
Location: Chelsea, Quebec, Canada
Contact:

Re: Gentry flotation and HP calculations - Any available?

Post by Mr Hot Rod » Mon Jun 07, 2010 7:55 am

Glenn :

I received your PM and decided to post to the Forum since the topic keeps coming up ...

We've developed an Excel spreadsheet for calculating flotation foam requirements for the Glen-L Hot Rod. I gave Bruce Dow a copy of the spreadsheet which he deftly modified to suit his Monaco.

Disclaimer : The spreadsheet can be a little tweaky -- use at your own risk ! Regulations are constantly evolving, so modifications may be required to suit current standards.
Other links :
Here's a link which may provide some inspiration on how to install flotation foam billets. We installed most of the foam up high under the deck before laying the deck. Not much help when you're trying to retrofit to a finished boat, but useful if you're still in the build phase !
Please let me know if you have any problems loading the spreadsheet. If you have any questions along the way, post them to the Forum so we can expand our knowledge base.

Hope this helps !

____________________
Paul Kane
Kane Custom Boats Ltd.
Chelsea, PQ

Building the Glen-L Hot Rod : http://www.kanecustomboats.com
Last edited by Mr Hot Rod on Mon Mar 12, 2012 9:21 am, edited 1 time in total.

Nova SS
Posts: 2434
Joined: Sat Nov 15, 2003 10:42 pm
Location: Stirling, ON

Re: Gentry flotation and HP calculations - Any available?

Post by Nova SS » Mon Jun 07, 2010 8:50 am

I didnt see an answer for the HP part of the question. With an inboard powered boat there normally is not a max HP limitation like there is for outboard powered boats. The formula's I've seen deal totally with outboards. If you check out the inboard plans on the Glen-l site HP is not mentioned normally weight or cubic in of the motor is mentioned but not HP.

User avatar
Bill Edmundson
Posts: 11682
Joined: Wed Nov 23, 2005 6:45 am
Location: Birmingham, AL, USA
Contact:

Re: Gentry flotation and HP calculations - Any available?

Post by Bill Edmundson » Mon Jun 07, 2010 2:27 pm

For my inboard the HP limit was my wallet :!: :wink:

Bill
Mini -Tug, KH Tahoe 19 & Bartender 24 - There can be no miracle recoveries without first screwing up.
Tahoe 19 Build

Trackhappy
Posts: 1412
Joined: Wed Feb 17, 2010 5:42 pm
Location: Sunshine Coast, Queensland, Australia. Building Gentry.

Re: Gentry flotation and HP calculations - Any available?

Post by Trackhappy » Mon Jun 07, 2010 5:37 pm

Nova SS wrote:I didnt see an answer for the HP part of the question. With an inboard powered boat there normally is not a max HP limitation like there is for outboard powered boats. The formula's I've seen deal totally with outboards. If you check out the inboard plans on the Glen-l site HP is not mentioned normally weight or cubic in of the motor is mentioned but not HP.
There seems to be another option for the maximum HP, being a maximum speed determined by the builder from testing turning standard corners at speed and measuring the maximum angle and freeboard. You have to have a speedo and have to have a plate visible to the driver stating the maximum safe speed. At least that is do-able. I don't like this having to have plates all over the place though, spoils the look of a nice Mahogany runabout.
By the time I have built a boat, I'll be ready to build a boat....

Trackhappy
Posts: 1412
Joined: Wed Feb 17, 2010 5:42 pm
Location: Sunshine Coast, Queensland, Australia. Building Gentry.

Re: Gentry flotation and HP calculations - Any available?

Post by Trackhappy » Mon Jun 07, 2010 5:40 pm

Mr. Hot Rod,

Thanks for all that, I guess I missed it when I searched the site. I will work through all this information and see what comes out. As you say, it is much easier to fit flotation at the building stage, which is why I asked now. Hopefully it will jog others memories at the right time as well.
By the time I have built a boat, I'll be ready to build a boat....

User avatar
billy c
Posts: 2403
Joined: Sun Oct 15, 2006 7:59 pm
Location: NH
Contact:

Re: Gentry flotation and HP calculations - Any available?

Post by billy c » Mon Jun 07, 2010 5:47 pm

Are you sure these standards apply to you?
it looks like they are addressing manufactured boats for sale and not homebuilt. We have similar standards for manufactured boats in the US also but they do not apply to homebuilt craft.
-Billy
(insert Witty phrase here)
Billy's Belle Isle website

Trackhappy
Posts: 1412
Joined: Wed Feb 17, 2010 5:42 pm
Location: Sunshine Coast, Queensland, Australia. Building Gentry.

Re: Gentry flotation and HP calculations - Any available?

Post by Trackhappy » Mon Jun 07, 2010 6:04 pm

billy c wrote:Are you sure these standards apply to you?
it looks like they are addressing manufactured boats for sale and not homebuilt. We have similar standards for manufactured boats in the US also but they do not apply to homebuilt craft.
-Billy
Yep, they specifically mention homebuilt if you are the builder. "Second Hand" is exempt, but then they state that it is not second hand if you are the builder and only user of the boat. Upon first sale to the public it must have a plate fitted. I am starting to wonder about Insurance on her now as well, probably based upon this same requirement. Have to check on that.
By the time I have built a boat, I'll be ready to build a boat....

Trackhappy
Posts: 1412
Joined: Wed Feb 17, 2010 5:42 pm
Location: Sunshine Coast, Queensland, Australia. Building Gentry.

Re: Gentry flotation and HP calculations - Any available?

Post by Trackhappy » Wed Jul 14, 2010 10:39 pm

Out of interest, I placed all the info I could find on Gentry into the spreadsheet and came up with a figure of 0.6 cubic metres of foam required to make her float. That is quite a bit to fit into a runabout, but I guess fill the areas between the deck beams, above the fuel tank and beneath the seats, will see as I go along where else I can squeeze some in.
By the time I have built a boat, I'll be ready to build a boat....

Ron Filsell
Posts: 104
Joined: Mon Mar 27, 2006 4:25 pm
Location: Sydney Australia

Re: Gentry flotation and HP calculations - Any available?

Post by Ron Filsell » Thu Jul 15, 2010 12:14 am

Trackhappy :Go ahead and build the boat. The information on an ABP can only be approved by either, The Builder. The Importer. or a Competent Person. A competent Person is idefined as a person who has acquired through, Qualification, Experience,or Training or a combination of these, the skills enabling that person to competently determine and approve the information on the plate.
If it sinks when launched, I guess you may not be competent, if not I think you are. :D :lol:
NSW Waterways dont want to see the plate, they just want you to tick the box that says you do. But I didnt say that. :wink:
This was edited from a reply I posted early this year and may help you. With regards flotation there are 3 levels the lower (now discontinued is INADEQUATE) The next is ADEQUATE and the last is POSITIVE. only POSITIVE needs support the boat fittings and crew.
ADEQUATE only means the boat will float at some attitude and support people in the water. From this description its easy to establish why INADEQUATE is now discontinued.
Regards, Ron.

User avatar
BruceDow
Posts: 2132
Joined: Sat Jun 17, 2006 2:21 pm
Location: Toronto, ON, Canada
Contact:

Re: Gentry flotation and HP calculations - Any available?

Post by BruceDow » Thu Jul 15, 2010 2:32 pm

Trackhappy wrote:Out of interest, I placed all the info I could find on Gentry into the spreadsheet and came up with a figure of 0.6 cubic metres of foam required to make her float.
Hmmmm.... you might want to double-check.... (or I should!!!)... I built an 18' (5.5m) Monaco with a 283 v8. Using that spreadsheet and my input, I needed almost exactly half of what you came up with (296 Liters or approx. 11 cu. ft.). I can't see our boats being that different.

If you would like to PM me with your eMail, I'd be happy to send you my file for comparison.
Bruce.

~~ Do what you love, and love what you do. ~~
~~ To me - only my boat is not yet perfect. Everybody else's is to be admired for I know the path they have walked (Dave Lott, 2010) ~~
Dow's Monaco Project

Trackhappy
Posts: 1412
Joined: Wed Feb 17, 2010 5:42 pm
Location: Sunshine Coast, Queensland, Australia. Building Gentry.

Re: Gentry flotation and HP calculations - Any available?

Post by Trackhappy » Thu Jul 15, 2010 4:00 pm

Bruce Dow wrote:
Trackhappy wrote:Out of interest, I placed all the info I could find on Gentry into the spreadsheet and came up with a figure of 0.6 cubic metres of foam required to make her float.
Hmmmm.... you might want to double-check.... (or I should!!!)... I built an 18' (5.5m) Monaco with a 283 v8. Using that spreadsheet and my input, I needed almost exactly half of what you came up with (296 Liters or approx. 11 cu. ft.). I can't see our boats being that different.

If you would like to PM me with your eMail, I'd be happy to send you my file for comparison.
Thanks Bruce, will do. I must admit I guessed on weights of some things, such as the V8. I will be using the 350 Chev with Velvet drive and possibly fresh water cooled so that adds quite a bit. Anyhow, I will re-visit and see what comes.
By the time I have built a boat, I'll be ready to build a boat....

Post Reply

Return to “Power Boats”