Avon Redstart engine submarine!

[ithet]

I have an Avon Redstart dinghy which came with the boat. It is in good condition despite being well used and has no repairs. It can just take the four of us if a bit "wobbly" underway. It is not often used, but essential when anchored. Last year however, I used it for the first time with my Tohatsu 3.5 2 stroke. I found that there was a great tendency for the engine to roll itself around backwards, along with the clip on transom. The problem occurred to the point of being dangerous as I could not use more than low throttle, and eventually I had to be towed as I was being swept away by the tide. Is this a common problem with this type of dinghy or operator error? I found that the problem was less if the tubes were really hard, but of course they sometimes go softer in the evenings. Also I had previously adjusted the engine bracket to be more slanted as I had used it on another boat with a more slanting transom - this meant that the leg was slanting out away from the transom of the avon. Could the resulting down thrust have been enough to cause this problem and it will be OK when readjusted?

What are other's experiences of using round-tail dinghies, is this is a common problem? I have been looking at alternative transom ones, but a 260 would still have less space for four and take much more stowage space.

Thanks

 

[Hadenough]

Horrible things, I've just sold the Redcrest that came with our boat. They have a huge fan base mainly I guess from people who like to roll them up to store aboard. They blow up quickly too with a good pump. But as you have discovered unless they are pumped really hard, use with an outboard is a joke. I'll duck and wait for the flak now.

 

[TonyBuckley]

But as you have discovered unless they are pumped really hard, use with an outboard is a joke.

I got rid of mine too. The tube would change pressure too often as the ambient temperature changed - it was a pain! Replaced with one that has a nice wooden transom - so much better.

 

[TQA]

You have already found the answer. Keep the tubes pumped up hard. I used mine with floorboards and this helped. I even had an 8 hp on while I was fixing the eggbeater, low throttle only of course.

Also don't use a lubricant when fitting the mount onto the tubes.

 

[Zagato]

You could always swap it for a larger rigid transom model. I found the 3.5 Tohatsu even quite heavy for my old solid 10' GRP boat and balanced the boat better by sitting more forward with an engine extension control arm about £20. It is a heavier 4 stroke though about 18KG.

I read a dinghy comparison article yesterday saying that round tails were selling less for the rigid transom models with tubes that extend rearwards to help the balance. The Honwave, then Avon/Zodiac then Waveline, Excel etc came out best by the way...

I have a 1994 Hyperlon 2.8 Avon Rover with slatted floor and it suits me fine and rolls small enough to put in my cabin or cockpit locker. No worries with it being left out in the sun either! I see loads of them still about being towed or on the back of boats. Our dinghy park is made up almost exclusively of old Avons

I had a moment in it recently when I thought it was losing air but it was just because I had more weight up front than usual

 

[Tranona]

4 people in a Redstart is way overloaded. The boat has a recommended maximum of 2hp. Yes, what you have experienced is common and made worse by trying to operate it outside the design limits. Keeping tubes at full pressure is important.

When the boat was originally designed in the 1960s the intended engine was a Seagull 40 minus and a maximum of 3 people and if used like that is perfectly adequate.

So, smaller engine and less payload or bigger dinghy.

 

[ithet]

Yes I am aware that 4 up is outside limits. To be honest I was originally thinking of swapping for a SH Redcrest which would still fold up well. But having had this issue using any sort of revs from the 3.5 (even 1 up) I am reconsidering. I think the engine power issue is probably true as it seemed to go OK with the old Mercury 2.5.
The answer is probably going to be to go for a solid transom (of about 260 and still not rated for 4 people!) and carry some fenders off the pushpit.

 

[Tranona]

The problem with modern engines is not just the power but the weight and the prop is deeper in the water. The folding under on round tails can be reduced in the latest designs by having a rigid floor, but then you start to lose the benefits of the older design which was its capacity and ease of folding.

There isn't an easy answer because as you say rigid transoms lose carrying capacity, are heavier and more difficult to stow. Not sure carrying fenders will do any good. The carrying capacity is a function of the space and size of tubes - another compromise as larger tubes means less space! Realistically you cannot carry 4 adults in a boat less than 3m.

 

[ithet]

Not sure carrying fenders will do any good.

Sorry Tranona, I meant that the bigger folded transom dinghy would mean I have to move some fenders out of the cockpit locker onto the pushpit to store the dinghy in there!

 

[NormanS]

It's like lots of other things in life. If you do it properly, you'll be alright, but if you overload the dinghy, don't pump it up, overpower it, and don't adjust the outboard angle correctly, then yes, things might not go entirely to plan. It's up to yourself, really.

 

[Tranona]

Sorry Tranona, I meant that the bigger folded transom dinghy would mean I have to move some fenders out of the cockpit locker onto the pushpit to store the dinghy in there!

Yes, I see! And develop strong biceps. If you have room might be worth considering a teak grid platform with the folded dinghy on top. Bit exposed but saves the huffing and puffing to try and get it in a locker.

 

[ithet]

teak grid platform with the folded dinghy on top

I dream..

The previous owner carried the folded dinghy tied accross the hatch, but I would prefer it out the way.

 

[Tranona]

I made one for my Eventide 26 from a Howells kit and a custom built stainless frame. Fits between the hatch garage and the mast. So successful also made one for my Bavaria 37 so I can have the choice of dinghy or liferaft on the platform or in the locker. Enjoyable to make, but the steelwork can be a bit pricy. Whole lot was about £300.

 

[ffiill]

4 people in a Redstart is way overloaded. The boat has a recommended maximum of 2hp. Yes, what you have experienced is common and made worse by trying to operate it outside the design limits. Keeping tubes at full pressure is important.

When the boat was originally designed in the 1960s the intended engine was a Seagull 40 minus and a maximum of 3 people and if used like that is perfectly adequate.

So, smaller engine and less payload or bigger dinghy.

My Seagull Forty featherweight (now approaching 50)more than adequately pushes my modern slatted floor transomed dingy along at a good speed-no need for big ouboards unless you have a hard v floored or airdeck dingy.

 

[Blueboatman]

If you take the painter back and thru the Avon o/b bracket this will help. As will plywood floor kit.
B4 the current huge range of inexpensive rigid inflatables, there was fair ingenuity at creating a better Avon tie between o/b bracket and floor.
The OPs description of an overloaded redstart, an overpowered heavy motor and an outgoing tide/assist.. Well, that's evolution folks too!

 

[ithet]

The OPs description of an overloaded redstart, an overpowered heavy motor

I think I explained that I had problems even when 1 up (I am 12st). The Tohatsu 3.5 two stroke is a small engine and weighs just 13kg! The weakest engines available nowerdays seem to be 2.5hp. Other posters have suggested that the Avon was designed for the dynamics of older engines. However the general consenus is that round-tails are not good with outboards. I had always known that they were not ideal with outboards, but did know how dangerous they could become in less than ideal circumstances.

 

[Blueboatman]

Sorry, I loved your thread title, because submarining is what they try to do!

Even with a 3.5 Yamaha Malta on the slightly bigger Redcrest, the stern bobs and curtsies v politely over the waves in the cool of an evening return ..

 

[Zagato]

The previous owner carried the folded dinghy tied accross the hatch, but I would prefer it out the way.

Not great if that is the only means of escape in an emergency - fire, etc.

I like the sound of Tranona's rack if you have a big enough boat.