With that combo, and the weight you are mentioning, getting on plane should be doable. However it would be marginal, and a small amount of additional weight could make all the difference between getting on plane and not. If you can find and manage a more powerful motor, you will have a lot more leeway, and not need to add up every ounce of cargo (and inquire of your passenger's weight ) before setting out.
With a +4m boat, a trailer will make things much more safe and convenient, rather than assembling & disassembling with each use.
If you plan to assemble and disassemble each time, then having a van or pick up truck with a small hand crane, launching wheels (or launching dolly), and a good electric pump would make the assembly/disassembly far more pleasant and safe.
The boat would be kept on a trailer itself, but the motor needs to be stored elsewhere for security reasons so the 15 is a good weight for easy handling and lifting. The engine on the trolley rolls into the back of our estate car just fine.
Also, the boat needs to be able to be moved to and from the tailer - over a short stretch of sand and up and down a small slip ramp by hand - I have some large transom wheels here that I had planned to fit on the 3.8
I'm thinking with transom wheels the setup with a 15 engine would be more manageable to handle?
I'm thinking with transom wheels the setup with a 15 engine would be more manageable to handle?
Definitely. In my experience a 15hp 2-stroke is the biggest that is easily manageable. Plenty of people do manhandle bigger engines, but it's hard work!
It sounds like you plan to deflate the boat every time? Depending on the floor type that could be a pretty heavy boat and the motor would lite in comparison. It also won't fold up/roll very small.
I would recommend a trailer for it. Run it with the 15hp, and if it is underpowered upgrade to a larger motor. On a trailer you won't have to deal with lifting the motor on and off.
Hi Peter, sorry I should have said on the last post, the boat will be kept inflated on the trailer... I recently got a motorbike trailer ( see photo ) and will be modifying that ( somehow ! ) and add bunks to rest the tubes on.
Any advice or pointers on converting this trailer would be a great help !
I just replaced the wheel bearings and will get new wheel rims very soon as the current rims are starting to look like the Titanic.
The thought of having to setup and pack away the boat every single time is really off-putting.
Also being permanently on the trailer is better option for the boat fabric and reduce wear and damage in the long term ?
Interesting. I think your on the right track with the trailer, just a matter of tweaking. I'm assuming that the trailer would be dual purpose for the motor bikes & boats.
Not knowing the motor bike application, would it be feasible to put a flat plywood deck in the center section of the trailer? What if you were to build a platform bunk that could be strapped on the trailer deck?
If you had launching wheels, you could roll the boat on and off the bunk. The bunk could be unstrapped from the trailer and place on the ground (with the boat stored on it when your are using the trailer for the motorbikes.
Hello Prairie, those drawings show clearly what you have in mind, the bunk being removable I think is a great option. It wont be used for motorbikes again anytime soon - only the boat, but having the boat part removable keeps the options open for multi-purpose use, i love it.
1 thing about the trailer - the total width ( mudguard to mudguard outer edges ) is approx 100cm.
I'm not sure just yet about boat width, but imagine it will be atleast 140cm +
How is best to mount the wider boat bunks section needed ? and from what materials ?
2x4" timber cross sections across the width to overhang each side.... ( or steel / alloy box section I think may be a better choice ) perhaps U bolted onto the existing frame, then add 2 flat wide planks lengthways on top for the tubes to rest on....
The total length of the trailer from hitch to tailgate is only 3 meter, so will need to extend the existing hitch bar with some box section - possibly just bolted on...
The tailgate ramp would also not be needed...
I have a set of transom wheels here Prairie ready to fit, should make loading onto the trailer a simple task.
Are sibs ok on trailers being supported by just 2 bunks - one under each tube ?
You should see around 17kts with that (near 20mph) - our Aerotec with a lighter load touches 19 kts now and again but 17 - 18 is more realistic and 15 - 16 an easy cruise.
My Sib trailer originally started out life as this .......see pics 1-3.
Third picture is it with box detached.
I worked from what wou see in pic 3. I extended the draw bar with box section and then bolted u section over it and welded a winch post. I also made a wider axle which bolts on and off.
Bolted two 1 inch thick pine wooden carpeted bunks on to the top of the platform then added a middle bunk to support the front.
I dry launch as the electrics are integrated into trailer.
Bunks and trailer top carry box are interchangeable so can still use it as a camping trailer or for runs to the council tip when the sib is wheeled off of it.
Think you could do something similar by extending the hitch and adding a winch post and adding bolt on / off carpeted bunks.
With a fabric bottom, really wide bunks with a layer of EDPM/EVA foam sleeping pad on their top side will greatly reduced stress to the boat fabric.
As far as what material to build a bunk platform it depends on what materials and resource ar most handy. Do you weld or have a buddy who will weld for beer and have access to reasonably price aluminum rectangular tubing? Is so and aluminum skeleton frame with a marine plywood surface for the bunks (with said foam) would probably be the lightest and most durable.
Building the whole thing from plywood would be fine as well, as long as you coat it.
A small set of wheels on the back end of the bunk platform box and a handle on the front end would also make the loading and unloading of it on the trailer much easier. The wheels should be just off the ground when the platform box is resting on a flat surface, but would contact the ground when it's front end is lifted.
Kaman I'm really liking your setup, it is nice and simple yet perfectly functional for its purpose. Some nice welds on that aluminium there ! did you do it yourself or have a shop do it ? Do you have any other photos of the trailer and of underneath? - I'm interested to see how you attached the wider axle.
Would you recommend a wider axle on mine or should it be fine with the current 100cm width ?
Prairie the wheels on the rear of the bunk sound a great idea and being able to lift the front to pull the boat on would be so much easier, do you have any photos of such a setup to ?
A friend works at a small shop but they only use mild steel, don't think they have the gear to weld aluminium but i'll find out tomorrow
Hi HighlandR.
I widened my axle from 110cm to around 180cm.
Much more stable.
Axle is 40mm box section.
Held onto the two metal runners on the underside of trailer by welding two plates onto box section and securing with 4 x m12 bolts just like standard axle.
Not got too many pics of trailer here is the ones I can find.
The lower the trailer is the easier it will be to dry launch and recover if you intend to go that route with the help of transom wheels.
I use a metal bar and rope rigged to the bow fixings (see pics) to lift bow.
With the wheels down Sib rolls on and off the trailer with ease.
I use carpet padded ratchet straps to secure it to the trailer.
I also utilise the transom towing eyes by clipping a strong rope horizontally between the two, then attaching the winch to pull the Sib forward and secure to the carpeted pad on the winch pillar.
I can also use the winch to pull the Sib onto the trailer once the bow is sitting up on the bunks.
Hope this helps.
Happy Sibbing!
Kaman thanks for they pics, I can see myself using your trailer as a building block on converting this bike trailer here. The pole to hold the bow up for draining is a nice touch
Are the bunks level with the road, or are they set on slight incline to lift the nose preventing build up of water while sitting in garden or being towed in the rain etc ?
Having sold the other 3.8 sib ( the one with the 2 chamber issue !! ) I've managed to get my hands on a slightly newer, deal has been done and now have a zodiac 4.2 - just been delivered today.
The main reason for buying this was that it is hypalon and has 5 chambers instead of 2 ( no thoughts of putting foam balls inside the tubes now ! )
also being slightly bigger the deck space should be more comfortable, and it seems to be a good quality boat.
The floor is ply coated with grp - which is pretty heavy, but not much heavier than the old floor that was in the 3.8 so can't complain !
The boat is pretty heavy... that is the only downside i can see so far, however I don't think it will be too heavy to manage on the large pair of transom wheels, also wonder if it will get on a plane with just the 15hp - but I'll find out soon enough !
what are your thoughts on the boat guys ?
I've never seen this model before - since it is an older boat will it be possible to find out more details/ specs etc from the serial number ?
such as weight, max HP, year of manufacture etc....
How does this boat compare against other sibs out there ?
If money was no object I'd have went bought a newer Bombard or futura like most of you guys have here but for an older boat - so far it looks to be just fine for us to go fishing - safe enough to go a mile or so off the coast?
) before setting out.
) and add bunks to rest the tubes on.
