Reply
 
Thread Tools Search this Thread
 
Old 15 September 2012, 11:28   #121
Member
 
Country: UK - England
Town: Truro-Cornwall & Brazil
Boat name: Bananas in Blue
Make: Humber Destroyer 5.5
Length: 5m +
Engine: E-Tec 115
Join Date: Jun 2007
Posts: 385
I've always thought my 1300GW trailer with 1000kg capacity was a little under engineered and it is defo less rigid than I would like. It only uses 2 80*40*3 chassis rails with no additional reinforcement. Its from one of the respected manufacturers who is well regarded on here and elsewhere but I am now wondering if it is up to the job.........

I gotta admit that all the other 1300 kg trailers I have seen have top and bottom rails on each side, not just one.
__________________

__________________
Markyboyo is offline   Reply With Quote
Old 15 September 2012, 12:50   #122
Member
 
Anchorhandler's Avatar
 
Country: France
Town: Huisnes sur Mer
Boat name: Raufoss
Make: Avon
Length: 4m +
Engine: Mercury 50
Join Date: Sep 2010
Posts: 789
Quote:
Originally Posted by HughN View Post
They were a "finger in the air", "not to scale", "the value of your investment can go down as well as up" type bodge I hasten to add!
Maybe, but the calculations i carried out were'nt.....the point was not to focus on the exact figures but to show the higher bending stress at the end of the rails.

Quote:
Originally Posted by Markyboyo View Post
I've always thought my 1300GW trailer with 1000kg capacity was a little under engineered and it is defo less rigid than I would like. It only uses 2 80*40*3 chassis rails with no additional reinforcement. Its from one of the respected manufacturers who is well regarded on here and elsewhere but I am now wondering if it is up to the job.........

I gotta admit that all the other 1300 kg trailers I have seen have top and bottom rails on each side, not just one.

I'm sure it will be fine...the case discussed in this thread involves only one particular home built trailer and dont forget, any trailer can be overloaded if it is not set-up correctly.

You have to take into account also that i never included a safety factor when working out the loadings ie: i never increased the loadings by a set percentage to take into account potential overloading, shock loading and wear on the chassis itself. By the same token though i never took into account the heavy angle bar u-bolted to the chassis rails just above the axle. As i mentioned previously, this angle bar will have a positive effect on the load handling ability of the trailer in question.

If i had to certify Jeepster's trailer i would agree that 800kg's is probably a sensible load limit as quoted by Indespension (not the 1300kgs he initially hoped for and subject of course to all components being welded together correctly).

As to why your trailer has a higher GW, this could be down to many factors like quality of steel used, set-up of the axle/rail, whether its a bunk trailer/swingbeam trailer etc...

Simon
__________________

__________________
C'est pas l'homme qui prend la mer, c'est la mer qui prend l'homme....
Anchorhandler is offline   Reply With Quote
Old 15 September 2012, 15:36   #123
Member
 
Country: UK - England
Town: London
Boat name: Jeepster
Make: Marina 16 GT
Length: 5m +
Engine: Outboard, Petrol, 30
Join Date: Sep 2012
Posts: 52
Quote:
Originally Posted by Anchorhandler View Post
Yes actually, i do call myself a Chief Engineer....

The load is equally distibuted at both ends because, as i mentioned, i'm only intrested in calculating the stress in the side rails at the area they connect with the axle. This is the most critical part of any trailer.

Re-read post number 86 and you will see that i mention a 150mm area where the rails connect to the axle....this is represented in the drawings by the two black triangles....funny enough, spaced 150mm apart.


If you also look at the calculations i have given you in the same post (200 X2)+(210 X2)=820Kgs, i thought it would have been obvious that the calculation was for one rail only considering i'm multiplying the loadings by two to account for the whole trailer.

I gave you an estimated maximum loading for your design of trailer at 820Kgs....based on my calculations. Have you actually checked what an Indespension 1100kg trailer is rated to carry? Funny enough i just have a few minutes ago... 800Kg max!
So not only are my calculations correct, it means that this fantastic trailer you've constructed is very nearly on the absolute limit for what your boat weighs....better not think of uprating that engine for a while then!

I also suggested you move the rear swingbeam forward to make it safer.....Look at the bending diagram and shear force diagram HughH has kindly uploaded and pay rarticular attention to the high bending/Shear force at the rear of your trailer (P.S. Thanks for taking the time to do this Hugh).

Finally, look at the calculations YOU have used and exoplain to me what is wrong here....Where did you get a 440 odd tonne load from?
Yes, thanks HughH. But what 440 tonne load??? Look at it again. The units are in Newtons (hence the N in brackets)...4482.2N is 457kg.

Quote:
Originally Posted by Anchorhandler View Post
and, as Hugh also questions....where has the uniform loading come from??
But the loading is not uniform!...Its heavier over the rear swingbeam than the front swingbeam...As my model clearly shows.
In an earlier post I have even given you a calculated split in the loading of about 68.6% over the rear swingbeam and about 31.4% over the front swingbeam.

Quote:
Originally Posted by Anchorhandler View Post
Both myself and others on here have genuinly tried to give you sound advise but you have chosen to refute it each and every time....
I dont remember there being much sound advice here...There have been an awfull lot of patronising and condescending comments aimed my way though...But of course most of them can probably be put down to the fact I dont have a RIB.
__________________
jeepster is offline   Reply With Quote
Old 15 September 2012, 16:24   #124
Member
 
Country: UK - Scotland
Make: humber
Length: 6m +
Join Date: Jan 2011
Posts: 20
"But of course most of them can probably be put down to the fact I dont have a RIB. "

or indeed a brain. Tis a good job you have something fit only for a canal where a duck's wake is as much of a sea as you will need to cope with, you would be surely dangerous in anything faster and at sea. I just hope I am never anywhere in the vicinity of the outfit on the road especially with my family in the car. If there was ever a case to support those who advocate compulsory MoTs on trailers this is it. And for a professional lorry driver (albeit unemployed for some reason) to have been working on such wildly inaccurate weight estimates is inexcusable.
On the other hand perhaps just a pillock with nowt else to fill his time but wind folk up.
Good rant that, most enjoyable.
__________________
dally is offline   Reply With Quote
Old 15 September 2012, 16:43   #125
Member
 
Anchorhandler's Avatar
 
Country: France
Town: Huisnes sur Mer
Boat name: Raufoss
Make: Avon
Length: 4m +
Engine: Mercury 50
Join Date: Sep 2010
Posts: 789
Quote:
Originally Posted by jeepster View Post
Yes, thanks HughH. But what 440 tonne load??? Look at it again. The units are in Newtons (hence the N in brackets)...4482.2N is 457kg.
But 44822.2N certainly isnt..... and your telling me to look again? Care to reconsider the results of your calculations now? (Oh, and check out the dimensions you have inputed for the rectangular section while your there.)


But of course most of them can probably be put down to the fact I dont have a RIB.

No, I think you will find that its probably because you only very recently joined this forum but promptly decided to teach some very experienced people all about how to load a trailer, how to lighten steel members and RSJ's, all about the mechanics and stress distribution in loaded beams and all along have refused to accept that you have been wrong in pretty much everything you have stated since you joined.


Who the f**k builds a braked trailer for a boat he doesnt even know the weight of anyway? Your no doubt going to keep towing it with your current tow vehicle as well i suspect.


Perhaps you may have better luck on one of the other dozen or so forums you have uploaded the same pictures and description to?

Speaking of forums....


17 foot boat across the channel...Possible? - Yachting and Boating World Forums


Did make me laugh...

Simon
Attached Thumbnails
Click image for larger version

Name:	beamloading11.jpg
Views:	103
Size:	9.9 KB
ID:	72235  
__________________
C'est pas l'homme qui prend la mer, c'est la mer qui prend l'homme....
Anchorhandler is offline   Reply With Quote
Old 15 September 2012, 17:40   #126
Member
 
Country: UK - England
Town: Todmorden
Boat name: Twentyfourseven
Make: Zodiac 550 pro open
Length: 5m +
Engine: Suzuki DF 90
MMSI: 235095113
Join Date: Jul 2011
Posts: 56
Quote:
Originally Posted by dally View Post
"But of course most of them can probably be put down to the fact I dont have a RIB. "

or indeed a brain. Tis a good job you have something fit only for a canal where a duck's wake is as much of a sea as you will need to cope with, you would be surely dangerous in anything faster and at sea. I just hope I am never anywhere in the vicinity of the outfit on the road especially with my family in the car. If there was ever a case to support those who advocate compulsory MoTs on trailers this is it. And for a professional lorry driver (albeit unemployed for some reason) to have been working on such wildly inaccurate weight estimates is inexcusable.
On the other hand perhaps just a pillock with nowt else to fill his time but wind folk up.
Good rant that, most enjoyable.
Love it. Jeepster has supplied the best Sh-te since SR4
__________________
gasman is offline   Reply With Quote
Old 15 September 2012, 17:47   #127
Member
 
tonto's Avatar
 
Country: UK - England
Town: Zummerset
Boat name: irven arlyss
Make: Humber Oceanpro
Length: 6m +
Engine: evinrude 135hp
Join Date: May 2012
Posts: 394
Quote:
Originally Posted by gasman View Post


Love it. Jeepster has supplied the best Sh-te since SR4
I am sure he is SR4!
__________________
tonto is offline   Reply With Quote
Old 16 September 2012, 05:42   #128
RIBnet supporter
 
Pikey Dave's Avatar
 
Country: UK - England
Town: South Yorks
Boat name: Black Pig
Make: Ribcraft
Length: 5m +
Engine: DF140a
MMSI: 235111389
Join Date: Feb 2008
Posts: 7,590
RIBase
Quote:
Originally Posted by tonto View Post
I am sure he is SR4!

11th post on page 1





As Willk said yonks ago
\l/ \l/ \l/ \l/ \l/ \l/ \l/ \l/
__________________
Rule#2: Never argue with an idiot. He'll drag you down to his level & then beat you with experience.
Rule#3: Tha' can't educate pork.
Rule#4: See rule#5
Pikey Dave is offline   Reply With Quote
Old 16 September 2012, 06:35   #129
Member
 
Country: Other
Town: Stanley, Falkland Is
Boat name: Seawolf
Make: Osprey Vipermax 5.8
Length: 5m +
Engine: Etec 150
Join Date: Mar 2006
Posts: 3,688
Quote:
Originally Posted by ShinyShoe View Post
If you want to save weight on the trailer just drop the lengthwise bars alltogether. Balance the boat very carefully on the axle and pull it by the painter. I'm not a structural engineer or anything but I'm sure you'll have reduced the trailer weight by the maximum amount possible and it'll stop these guys all shouting at you about the dimensions of the box section.
__________________
A Boat is a hole in the water, surrounded by fibreglass, into which you throw money...

Sent from my Computer, using a keyboard and mouse
BogMonster is offline   Reply With Quote
Old 16 September 2012, 13:03   #130
Member
 
Country: UK - England
Town: Plymouth
Length: 6m +
Join Date: Mar 2011
Posts: 2,693
Have you been drilling holes before Jeepster ?

Peter @ Boatsandoutboards4sale ~ askboatsandoutboards4sale@sky.com ~ 07930 421007
Attached Thumbnails
Click image for larger version

Name:	image-3204675185.jpg
Views:	225
Size:	84.0 KB
ID:	72242   Click image for larger version

Name:	image-1536081305.jpg
Views:	187
Size:	93.2 KB
ID:	72243  
__________________

__________________
Boats&Outboards is offline   Reply With Quote
Reply

Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off





Copyright 2002- Social Knowledge, LLC All Rights Reserved.

All times are GMT -5. The time now is 05:36.


Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2017, vBulletin Solutions, Inc.