twin outboards on sib?

White2505 · 25 August 2011, 15:34

Hi all,
looking for some advice.

Pretty sure I'm going with a 3-4m SIB (depends on what comes up at the right price!)

I'll be primarily using it for fishing and messing around on a tidal estuary and inshore off the North Devon coast (tidal range is typically between 3 and 10m)

obviously safety is one of my primary concerns, don't want to be disappearing off into the Bristol channel!

A sib in the range I'm looking at typically looks like it is rated for around a 10hp outboard.
Is there any reason not to go with a couple of small 3-5hp outboards to give myself that safety margin if one engine won't start?
or will a typical sib struggle with the transom weight of two 5's compared to a single 10?

hope that all makes sense.

Poly · 25 August 2011, 15:40

With big currents / tides 3HP is probably going to struggle to get you home at a sensible speed. Possibly fine for an aux which is a fall back position and where you might limp to somewhere, or keep yourself in one place waiting for a tow. Bear in mind that 2x3HP is twice as likely to develop a fault with one of the engines as 1x6HP and so see you using a single engine twice as often as you would need to revert to an aux with a bigger single. Its also a lot of extra weight and hassle which I don't think you really need. Probably better to spend the servicing cost of 2 engines on looking after 1 really well so it always goes!

willk · 25 August 2011, 16:17

Twins on a SIB is going to wreck yer head - in so many ways.

My advice is buy a decent engine (not new perhaps, but a good example with some history) and keep it well serviced. Learn how to sort the basic problems that occur at sea and carry a decent spares/repairs kit. After that make sure you have a very good anchoring system and a VHF. Help is never far away.
Bear in mind that IF the wind and/or tide is going the way you want, a pair of oars will be very useful and never fail to start

Common engine problems are:
Water in fuel (easily guarded against)
No fuel - ditto
Damaged fuel line - carry spare
Broken starter rope - carry spare and tools
Oiled spark plugs - carry spares and tools

There is some useful chit chat about SIB equipment and spares here: Linky

Mollers · 25 August 2011, 16:31

I'd go for a pair of VHF or even a personal EPIRB rather than extra outboards. Don't think that all outboards are tempermental nightmares. A well serviced modern O/Bs are pretty reliable.

White2505 · 25 August 2011, 16:46

Thanks for that.
I've done a fair bit of kayak fishing in the past so I'm used to getting places under my own steam, carrying the appropriate safety kit and general anchoring principles. I've also done my fair share of accepting that the tide is too swift for me to work against and waiting it out
having an engine will be something of a new experience though (although I'm used to working on cars and bikes historically.)
I just don't like the idea of being a mile offshore and flaming engine refusing to start!

prairie tuber · 25 August 2011, 16:54

Generally, you don't see twin outboard set ups on SIBs that are less than 5m long. Where you do see twin OB setups on these larger SIBs are with military or commercial applications rather than for civilian use. You won't get nearly as much propulsion from two 5hp outboards as from a single 10hp outboard.

With 2-3 adults in a 3-4m SIB, a 10hp outboard would be marginal and might not get you on plane. Most 3.5-4 meter SIBs will have max hp ratings much higher than 10hp, more like 50hp for some of the more stout 4.0m SIBs. I would be wary of the construction quality of a 4m SIB with a 10hp max rating.
If you have the space inside, you could take a 3-6hp outboard along as an auxillary. You would likely find that a 3hp outboard will crawl you back to shore in calm conditions but be useless in a current.

White2505 · 25 August 2011, 17:02

I'm looking at around 3m length as my ideal starting point. only looking to carry 1 normally with occasional 2 and three person trips.
Not figuring on taking on large swell/current combinations. mainly looking at the safety angle which judging by the posts isn't the issue I though it was as the engines sound like they're fairly reliable if looked after. also looking to do this on a sensible budget so brand new 10hp outboards are out of the question!

prairie tuber · 25 August 2011, 17:08

As for self propulsion in a SIB, their width makes them pretty awkward for that. If in shallow water (less than 2m) a long push pole is by far the most effective. Assuming deeper water, if you are alone, oars are the only way to self propel. Paddles will work if there is a least 2 of you (preferably more) each with paddles.

frankc · 25 August 2011, 17:09

In addition to the weight of two outboards, you need transom width. The advice of a VHF and good anchoring system is good, but you also may want to carry a sea anchor if you are really concerned, and a GPS would be invaluable to tell the rescue folks where you were.

Give the rescue folks your position and throw out the sea anchor. They can probably plot the position vs time by taking into account the currents in the area where you are when you report the trouble.

Have been using outboards for 40+ years, and only had two occasions of having to depend on wood propulsion to get home. One was a failed lip seal which had given good warning before failure and a shear pin without tools to change it. It is unusual for a two stroke to let you down if you give it proper maintainance.

prairie tuber · 25 August 2011, 17:17

Quote:

Originally Posted by White2505

I'm looking at around 3m length as my ideal starting point. only looking to carry 1 normally with occasional 2 and three person trips.
Not figuring on taking on large swell/current combinations. mainly looking at the safety angle which judging by the posts isn't the issue I though it was as the engines sound like they're fairly reliable if looked after. also looking to do this on a sensible budget so brand new 10hp outboards are out of the question!

If you come across a gently used 10hp 2 stroke at a fair price, it will offer some advantages over the newer 10hp 4 strokes - particularly weight and possibly less maintenance costs. Reliability should be good fore either 2 or 4 strokes.

Are you planning to assemble & disassemble the boat with each use? If so how much outboard weight are you comfortable handling? For the same weight, you can get a more powerful 2stroke than a 4 stroke. Are there any differences in the boat regulations in Britain depending on whether the boat is powered by more or less than 10hp (as is the case here in Canada)?

White2505 · 25 August 2011, 17:45

cheers for the advice. I've got room at home to keep it assembled on a trailer which will make life easier. Obviously I don't want to have to do 'an Arnie' to move it around though.
I'm not aware of any additional regulations for over 10hp here in the UK unless the more knowledgeable folks on here chip in to say otherwise.
Still early days for me and I'm trying to make sure I make the right decisions now before committing to parting with any money!

prairie tuber · 25 August 2011, 21:32

Good to hear that you'll keep it assembled and on a trailer it will make it far more convenient to use, and you will in turn use t much more frequently. If being trailered, I would consider a more powerful outboard. If you are looking for a used outboard, you might not find a big difference in price of outboards in the 10-25hp range.

Turbodiesel · 25 August 2011, 22:23

Plus trying to steer twin tiller arm engines is always a little difficult!

Cookasaurus · 26 August 2011, 14:03

Good points mentioned here. Just for interests sake there is a vid on youtube (damd if i can still find it) where someone has put twin outboards on a sib if anyone can be bothered finding it and posting a link on here for the entertainment value

Cookasaurus · 12 September 2011, 09:00

Haha found it

2 x 6pk yamaha achter zodiac 2.85 xD - YouTube

White2505 · 12 September 2011, 09:12

excellent!

my original plan to keep it on a trailer fully assmebled has been vetoed by she who must be obeyed.
SO at the moment I'm assembling as required. I've got better at this. I may end up berthing it at the local yacht club in due course.

I have now found a nice cheap air cooled volvo penta 4hp to get me out on the water whilst I hunt out something a bit more mental for fun and hijinks later.

Cookasaurus · 12 September 2011, 09:23

Good stuff on getting on the water!

I was going to get a trailer also for ease but cost, space and the 25hp motor bouncing on the back wasn't ideal. So yeah I'm setting up each time also like you! Just remember a few tips (presuming you have same as me and these aren't new):

-Semi inflate before putting floor in
-chuck metal spacer under boards
-Use airpump with valves open to get initial air quantity

White2505 · 12 September 2011, 09:28

thanks for that. the oars under the floor was the key to getting those tricky edge stringers in. everything else was a breeze.

Crusher · 12 September 2011, 09:33

Quote:

Originally Posted by Cookasaurus

Haha found it

2 x 6pk yamaha achter zodiac 2.85 xD - YouTube

Hilarious! Only problem is it looks like it needs two helms!

Sent from my iPhone using Rib.net

9D280 · 12 September 2011, 10:29

Quote:

Originally Posted by Turbodiesel

Plus trying to steer twin tiller arm engines is always a little difficult!

I believe the thing you are after to solve that problem is called T.E.S.T. (Twin Engine Single Tiller) Basically a tiller that also has a couple of short bowdens attatched to allow both throttles to work off one twist grip. Then link engines with aconnectiong bar as you would on a standard twin setup.

I'm suire something similar could be rigged at the lower end of the scale!

Oh, and as for the "twice as heavy" comments, not necessarily. I'm fed up writing it all, so do a search for "Twins" "weight" and my ID. Then go find the brochures for your chosen engine(s). You may be surprised....