13ft Achilles SIB (SGX-132) and 30hp 2s

joey_1987 · 01 May 2010, 11:39

Hey everyone,
I already posted this in the RIB section by accident but haven't had any hits. I am thinking about purchasing an Achilles SGX-132 SIB and already have a 30hp Mariner(Tohatsu) 2s outboard which I would put on it. I am wondering if anyone can tell me the sorts of speeds I would get with 2-3 people on board? Would it be worth going for one with a 40hp? Am also considering a 3.5m RIB as a possible alternative but they can only take 25hp. It will be used for watersports, rough weather play, some long distance cruising.
Thanks.

C-NUMB · 01 May 2010, 14:40

The tohatsu 25/30 is not a particular high torque engine. Based on a old boat magazine
test(done with a traditional open GRP boat) speed with 2 persons WOT was about 23 knots, but with 4 persons only 17 kn. Dropping 500 rpm, speed went down to 13 knots.....

But GRP boats are heavier than sibs, so with right prop and 3 persons, guess full speed close to 23 kn then?

Clipper · 02 May 2010, 03:05

Where in Melbourne are you based Joey? what type of long distance cruise's were you planning? Port Phillip or Bass Strait?

joey_1987 · 02 May 2010, 10:05

Am on the mornington peninsula. Only around PPB I would think, may go out the heads and have a look around the portsea area. What size quicksilver do you have with the 18hp tohatsu? Do you get good speed out of it?
Cheers.

Clipper · 02 May 2010, 13:38

certainly get very good speed out of my 3.4m quicksilver with the 18hp. it is quicker than my mates 3.8m with a 25hp. very light and maneuverable, i tow it along as a float when i dive. i have taken it out all over the bay, launched at flinders and shoot over to fingal/cape schank and even out to the islands around wilsons prom.

joey_1987 · 02 May 2010, 14:01

What model quicksilver do you have? the 340 sport is rated to 15hp but the tohatsu 18hp is sold as a merc 15hp anyway. Do you just use it by yourself or with others on board? Any idea of gps speeds? How do those small quicksilver inflatable hulls handle the waves? Sorry for all the questions.
Cheers.

Clipper · 03 May 2010, 01:12

I use a 3.4m hypalon Sport, current model.

Not sure of precise speed, haven't checked it on a GPS. However, my guess would be over 25knts at full pace with one person on board. I generally have two up, and occasionally 3, which isn't comfortable with all the dive gear.

The 18hp is within the weight bracket suggested for the quicksilver, so that is why i use it. Apparently tohatsu outboards are just modified 15hp mercs as you stated.

The duck handles the waves fine, as mention it is so light and maneuverable that i generally avoid throwing passengers, and with the extra power can bail out of situations quickly.

Personally, i dont dive off the duck when the weather is poor, but have been caught out in changes of about 20-25kt SW, and a bit of swell. I felt very comfortable with the boat and at no stage thought I was in danger.

I noticed that you want to do rough weather play, personally i think RIB's are better for that.

I have a few mates with 3.8m Quicksliver duratex/Achilles, with 25hp. these are slighty less maneuverable, but still handle all conditions we dive in with ease.