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Avon 3.1m Rib - Project

Mon Sep 11, 2017 4:18 pm

This thread will be a work in progress and I suspect it may take a while to complete.

Introduction

Pete came with us to Scotland and used his boat for one day. Unfortunately, his boat did not perform well enough so couldn’t take it along with the group. While driving home, Pete mentioned how he enjoyed driving it for one day and wanted to improve it so he could take it out for days trips. Pete asked me if I would mind helping him to enhance the boat to meet his requirements, and eventually, I caved in and came up with a compromise. I will help him if he does most of the manual labour as at the moment my time is very limited.

Pete has had a lot of good feedback from members on what probably needs to be done.

How successful this project will be, depends on Pete - His cash flow, his time, his workmanship, and motivation.

Pete seems to struggle using this forum on his iPhone, so I'll will keep this thread up to date.

Goals
1. The boat has to be safe
2. The boat has to perform with 2 adults on board
3. Have something by May 2018

I suspect he will end up with 2x 10Lt fuel tanks up in the front of the boat. A small RIB jockey console mounted as close to the front as possible and a 15HP 2 Stroke engine.

Boat Spec
Avon 3.2m Rib (This is what I think, if anyone knows for sure let me know)
9.9hp 1984 Johnson 2-Stroke Engine
Remote steering and Throttle

The first job
1) See how far his remote steering and Throttle cables reach as this will depend on the location where the console is mounted
2) Strip everything off the boat (Console and Engine) while taking loads of photos.
2) Research if the Johnson 15HP Powerhead on a 1986 engine is the same as a 1974 engine. Pete has a lovely 1974 15HP powerhead which has very little use.
Attachments
boat.jpg
Last edited by James on Tue Sep 12, 2017 9:57 am, edited 1 time in total.

Re: Avon 3.2m Rib - Project

Mon Sep 11, 2017 9:17 pm

James
More likely it's a 3.1. I don't think they did a 3.2
or maybe an avon rover 315
Isn't there a plate on inside of transom? I thought I saw one

is Pete going to utilise that console he has?

Re: Avon 3.2m Rib - Project

Tue Sep 12, 2017 8:41 am

I didn't see a model on the plate. Next time I go round I'll have another look.

Pete just wants to use the boat for day trips, and not load it up as we did in Scotland so floor space isn't really a concern for him. He wants a jockey seat (I think that is the term) with a back rest. I have seen you can buy them separately, or you can buy a seat with a console included. There are a few second-hand ones on eBay.

Re: Avon 3.2m Rib - Project

Tue Sep 12, 2017 8:46 am

Ah, I just found the original advert when it was sold to Pete
https://uk.topboats.com/yachting/used-b ... -rib/fotos

Re: Avon 3.1m Rib - Project

Tue Sep 12, 2017 12:08 pm

James,
I am not sure what it is due to the pointy bow, I thought the rovers had a square bow, but could be wrong, they may have changed over the years.

Re: Avon 3.1m Rib - Project

Tue Sep 12, 2017 12:56 pm

The main plate where the serial number is has been removed for the remote steering.
This means we can't find the model of the boat. Not too much of a problem, it would be nice to know so we can see what mods other people have done.

Re: Avon 3.1m Rib - Project

Tue Sep 12, 2017 8:51 pm

We are going to start with the engine.

Pete has an engine already on the boat. The specs of the engine are

- Made in Belgium
- Style is Evinrude
- 10 HP
- AC Lighting - Rope Start
- Built in 1986

Since Pete's boat hardly moves unless it's at full WOT, we suspect the engine has had a hard life. Despite the PSI compression on both cylinders being good, I've noticed there is a small crack in the powerhead. This crack can only be seen when you zoom in on the image. We've decided to write off the powerhead.

Pete has a 15HP engine in his shed. The seller told Pete the engine was sitting on the back of a sail boat all it's life and hardly used. We took off a side plate and found the engine to be really clean. The engine still had the original protection paint inside. Due to the engines age, it uses the magneto electrical system. Spare parts are hard to find and provides a weak spark compared to the Capacitor Discharge Ignition system.

So the plan.... We will put the powerhead and gearbox from the 1974 engine in to the 1986 engine. This way, he gets a good powerhead while still maintaining the CDI electrical system.

Photos of the "low hours" 1974 powerhead
Attachments
20170327_183900.jpg
20170327_183841.jpg

Re: Avon 3.1m Rib - Project

Tue Sep 12, 2017 11:26 pm

Here is a photo of the issues with Petes 1986 engine.
I don't know if this is fixable or even worth fixing.
Attachments
20170416_115652.jpg

Re: Avon 3.1m Rib - Project

Wed Sep 13, 2017 11:07 pm

James
Hard to tell without seeing and measuring it in the 'flesh' :|
Basically, the block is aluminum with steel liners. Ideally there should be complete contact between both surfaces, liner and block/casing. The head gasket seals onto both surfaces, with the seal between the liner and cylinder head being the most important. If the steel liner has moved within the casing then compression could be lost. The steel liner should be flush or 1-2 thou 'proud' of the casing to ensure compression of the gasket. If the steel liner is below the casing then it's goosed because of the fracture allowing the liner to move downwards (hope this makes sense to you).
:cheers

Re: Avon 3.1m Rib - Project

Wed Sep 13, 2017 11:34 pm

I don't know the engine design but looking at the images I'd guess the gap between the liner and the block is from water ingress causing corrosion after the initial crack appeared. If that's the case then the block is scrap imo :(

If possible, make one good out of two bad.. rebuild it properly and have the reliability confidence.
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