Just to add a bit of substance to my earlier brief thoughts (via the app) now that I have a keyboard in front of me.
You said you want to beach it regularly
. If you actually want to beach it, rather than anchor off and swim / wade ashore, then I'd say GRP hulls are far from ideal - they seem to magnetically attract any rocks/stones on the beach and get scratched / chipped. Your Aluminium hull is therefore a good call. I'm not sure unprotected fabric (SIB) hulls are ideal for this either, transom wheels will be the echos you hear from the SIB forum - but at over 4m that is quite an unweildy beast to move on a couple of small wheels well behind the balance point. You've dismissed plastic - but actually plastic is one of the best materials for carefree beaching.
Landlockedpirate and others have covered a number of the other points I wanted to make, but all the same:
You are talking about taking 2 young children
. Young children aren't really best suited to perching on a tube or sitting on the floor/deck. I'd say this is especially so if you are busy helming and their is only one other adult on board. I'd be looking for an arrangement where the kids can get a reasonably secure seat. Even if that meant it wasn't a RIB.
You were talking about possibly taking 4 adults
plus kids (and presumably the associated gubbins. Any 4m boat will be "crowded" with six people on board, especially with fishing rods as you hinted at. Most boats are going to be sluggish with that load and only 20HP. Rigid hulls seems to perform better than SIBs when heavily laden. You've now suggested the future might involve towing toys. I think you'll need to decide to go less than 4m or more than 20HP to keep that a realistic prospect.
You were considering car topping and putting engine in the boot
. That's possible with some vehicles but it will take the entire boot, be awkward to do and leave almost no room for the other stuff that spouses and children seem to accumulate and need to take with them. With a "rib" it would also seem you get the worst of both worlds - it that you still have the kit faff of removing everything from the boat to transport it that you get with a SIB.
I think the comments about brands
are applicable not only to the engine (and there is no doubt that rightly or wrongly Yamaha's have more appeal than Parsun's and will be far easier to find someone willing to fix it) but also applies to the hull. Whilst Ribeye are not everyone here's cup-of-tea they hold their value reasonably well. They also have a reasonable after sales capability which you should be aware of when comparing prices. A return trip to the other end of the country because a valve is faulty would really put saving a few pounds into perspective.
I'm still not sure why you actually want a RIB
though. That might sound silly on a RIB forum! However the tube is a relatively expensive part of a small RIB/SIB (and a vulnerable one) so what benefits are you hoping to get from a RIB over other boats ?
Originally Posted by whisper
First of all forget the other family, they won't be coming out in the type and size of rib/sib your looking for. The only way they'll be joining you is if they also by a similar size package and join you for days out.
This is probably a fair point! The other time they can still come along is when its only a mile or two to the beach / deserted island you all want to have a BBQ on - then you can make a couple of trips to get everyone there.