Avon SR. 5.4 rebuild

nckalderson · 14 April 2015, 18:01

Hi Guys
I have my self a Avon sr 5.4 which I have completely revamping I have sunk a new custom built 123 ltr fuel tank, new console redoing the tubes with hypalon paint etc. I have redone all the seems on the tubes as they were looking tatty and putting a new strafing around the tubes. I have run run all cables under the deck with new hydraulic steering and electrics.
The one thing that I am doing is putting twin 60hp Mariners on her the year of both engines is 97 I have cut the transom wider to make room for both engines and have taken note of the weight and know I am 20 kg over the recommend working transom load which I can't see being an issue as I have my tank up front which weights in at 125kg full. If any one has done this befor or has any information regarding what I have done will be great to hear from you.
Here is some photos of where I'm up to and befor and after
Thanks
Nick

nckalderson · 14 April 2015, 18:07

Hi Guys
I have my self a Avon sr 5.4 which I have completely revamping I have sunk a new custom built 123 ltr fuel tank, new console redoing the tubes with hypalon paint etc. I have redone all the seems on the tubes as they were looking tatty and putting a new strafing around the tubes. I have run run all cables under the deck with new hydraulic steering and electrics.
The one thing that I am doing is putting twin 60hp Mariners on her the year of both engines is 97 I have cut the transom wider to make room for both engines and have taken note of the weight and know I am 20 kg over the recommend working transom load which I can't see being an issue as I have my tank up front which weights in at 125kg full. If any one has done this befor or has any information regarding what I have done will be great to hear from you.
Here is some photos of where I'm up to and befor and after
Thanks
Nick

nckalderson · 14 April 2015, 20:46

Hi Guys
I have my self a Avon sr 5.4 which I am completely revamping I have sunk a new custom built 123 ltr fuel tank, new console redoing the tubes with hypalon paint etc. I have redone all the seems on the tubes as they were looking tatty and putting a new strafing around the tubes. I have run run all cables under the deck with new hydraulic steering and electrics.
The one thing that I am doing is putting twin 60hp Mariners on her the year of both engines is 97 I have cut the transom wider to make room for both engines and have taken note of the weight and know I am 20 kg over the recommend working transom load which I can't see being an issue as I have my tank up front which weights in at 125kg full. If any one has done this befor or has any information regarding what I have done will be great to hear from you.
I will upload photos when I can work it out.

Thanks
Nick
Attached Thumbnails
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whisper · 14 April 2015, 22:37

Dude, I'm sorry to say this but I think you have made some big mistakes

The twin set up on a 5.4 goes on the top of the transom, not lower down so there was no need to cut the transom. Now with the extra weight you will just flood the boat, especially in reverse. And I would have thought that the engines will be at the wrong height.

There was another pic of the deck that had been cut down the middle, also not good dude, there is air tanks there.

The engines are over powered the tank is too far forward.

Sorry to bring bad news but someone has to say before you go any further.

nckalderson · 15 April 2015, 14:57

Hi mate thanks for you reply in a way I disagree as I have not cut the transom down only made it wider.
With regards to the air pockets I have blocked up the hull so it's a water tight compartment and will be filling with expanding foam.
The fuel tank fully loaded comes in at 123 kg plus my weight of 80kg plus a passenger. I respect what your saying but with the extra bouncy with the hull not filling with water I think that will be enough compensation for the extra weight if my calculations are right I'm only 20 kg over which is not a massive overload. I had a friend which had the old type Yamaha 140 v4 which is a massive load.

Thanks
Nick

biffer · 15 April 2015, 15:02

Don't fill it with foam. Just make sure it's watertight

matt h · 15 April 2015, 17:02

I totally agree with whisper. a SR 5.4 is ideal for up to 125 kgs on its stern, any more and it becomes unbalanced. if you made the transom aperture wider coupled with the extra engine weight you are going to have a VERY wet boat.. the air tanks are under the deck floor about 2.5ft from the rear of the boat. these also strengthen the floor where needed.
20 Kgs over the transom weight is a lot on a narrow beam boat. and def on a 5.4.

nckalderson · 15 April 2015, 19:01

Ok thanks guys project is to far to start changing it so there will only be one way to find out. And the hull is 100% water tight will keep you posted thanks

nckalderson · 16 January 2016, 20:13

Neil Harvey · 18 January 2016, 09:15

Whats with the plate on the transom? Did you realise Whisper and Matt were right? How did you build it back up underneath?

nckalderson · 18 January 2016, 11:28

I had a marine fabricator make it up its one plate raised to the level of the top transom. The engines sit perfect with the cavitation plate perfectly in line with where it should be in the water. The deck is completely water tight and the engines are not over weight with the transom plate I have had made up. She sits perfectly in the water not stern heavy. But thanks for the heads up. But so far so good

A1an · 18 January 2016, 19:14

Quote:

Originally Posted by nckalderson

The deck is completely water tight and the engines are not over weight with the transom plate I have had made up.

Blimey, that must be nearly 190kgs hanging off the back of that boat.

The transom may take it but it'll take all the fun out of what should be a lively little RIB.

nckalderson · 19 January 2016, 01:22

I disagree but watch this space

A1an · 19 January 2016, 07:05

Quote:

Originally Posted by nckalderson

If any one has done this befor or has any information regarding what I have done will be great to hear from you.

Thanks
Nick

Nick, since posting this thread you have heard from boat builders and people that have possibly OWNED more Seariders than you've seen and yet you still disagree with all their comments/suggestions.

Kind of pointless starting the thread really, but I'm sure you'll disagree.

matt h · 19 January 2016, 13:28

Nick. this will be sooo unbalanced and potentially dangerous and Insurance etc.. with that weight on a narrow beam SR will cause a lot of stress and worse as you have raised the transom height.
all you are doing is loading up both ends of the see/saw and the inevitable will happen at some point dude.
The SR'S with twins only had one baler and not two also.

Quote:

engines are not over weight with the transom plate

its not the transom plate thats the issue. the greater issue in the joins either side. If Avon had designed the Rib to take that weight then there would be no issue. but they didn't Nick

Pikey Dave · 19 January 2016, 14:47

Matt, you might not get a reply. Nick might be enjoying a little "contemplation time" alone in a quiet room😏

John Kennett · 19 January 2016, 15:17

I deleted his last post as I considered it abusive. At this stage he's still free to post though.

nckalderson please take note that it's OK for people to say that they think that what you are doing is a bad idea. It's not OK to abuse them.

A1an · 19 January 2016, 18:28

Did I miss a rant?

jambo · 19 January 2016, 18:53

Quote:

Originally Posted by A1an

Did I miss a rant?

You been sleeping again!!👍🍺

Sent from my iPhone using RIB Net

A1an · 19 January 2016, 18:59

No 3G at 2700ft today