Bonwitco 449 planing issue

[Benq23]

Good Afternoon, this is my first post on these forums as ive been searching the internet for help with my boat (Bonwitco 449) and cant drum up any specific answers

I recently got the boat along with a 2006 30hp Tohatsu 2 stroke, all went well at the viewing with the engine running up to speed etc but with us being novices we didnt really know what to check to ensure all was sound. looked good and as I expect happens a lot with first boat purchases we went for it and learned about the boat and engine properly with the experience of using it.

First trip out we went fully rigged with fishing gear, anchors, aux engine (Suzuki d5 4stroke on aux bracket) and three adults aboard so a significant amount of weight. got to sea and the engine pretty much failed on us, we limped it in at idling speed and discovered to our cost that the throttle cable was about seized and the throttle control pin was disconnected (plastic clip had disengaged leaving the throttle stuck at idle)

Fearing this would be a common occurrence and hoping to stave off escalating engine repair costs I spoke to a few people with knowledge on the matter and they educated me on proper maintenance and on the spot troubleshooting of common problems IE oiled spark plugs, carb cleaning and how to replace that damned clip when it decides to jump off the throttle control. As a result im comfortable with the engine and am able to keep it going well and up to max revs at sea without issue.

So....to the matter at hand. The bloody boat wont plane. no matter which tilt setting I put the engine at, no matter how we rearrange the weight (we have since been only 2 up) no matter what we do the boat will not get up on the plane even though it is clearly trying to with a frankly enormous wake when underway

I realise it is just a 30hp engine but was lead to believe that bonwitco 449's were an easily planed boat with very little power needed. at the moment i am getting displacement speed with it running at wide open throttle

The boat does feel exceptionally heavy to move about on the trailer when out of the water so I wonder if this may be a water ingress problem, or maybe I just need a bigger engine.

If any current or previous owners of this type of boat could weigh in with their opinion I would very much appreciate it



Cheers.

Ben

 

[gordmac]

Are you getting full revs but no speed? I believe outboard props have a rubber collar between shaft and prop which can slip under load.

 

[Benq23]

Yeah I am getting full revs and it is making quite a large wake as if its bogging down under the weight, boat sits well though and certainly dosent look overloaded IE sitting too low in the water, I may get a new prop to see if that makes a difference as I did wonder if it may be a spun prop

 

[gordmac]

I think you can align marks between prop and something to check for slip. If the engine is reaching max revs but the speed is down from where it was slipping prop seems likely.

 

[BruceK]

The boat is double skinned. Check for water.

 

[ari]

Could you get enough water in there to stop it planing? I'm not saying you're wrong, I genuinely don't know, but for example, if you put a 20 litre canister of water in the boat I wouldn't think that would be enough to stop it planing. Can you get more than 20 litres of water sandwiched between the skins?

 

[BruceK]

The OP said the boat felt remarkably heavy on the trailer. Considering these boats are around 200kg that should be the first port of call. His boat is double skinned with buoyancy chambers. These are probably foam filled and he wouldn't be in the first of several hundred to find it's sodden wet.
If in doubt take it to a weigh station. Here are the specs O Malley Auto Marine

 

[Davy_S]

I would check what Bruce says about the possibility of sodden foam (it does happen) secondly, weight distribution is critical, you have the weight of the engine on the transom, plus the weight of an auxiliary engine, battery and fuel tank near the transom? all this can make it too stern heavy, the engine tilt needs to be vertical or slightly tucked under to get it on the plane, 30HP is starting to get borderline with 3 onboard plus gear, but it should do it with 2 up, and weight moved forwards.

 

[Benq23]

Thanks so much for all the replies, how would you go about checking between the skins for water? is it going to be a massive job of removing the deck or is there a less serious method of checking? we have moved all weight as far forward as possible previously IE the spare fuel tanks and fishing gear, aux off the bracket and stowed forward. if it is indeed sodden what would be the likely cause? thanks again for you help so far

 

[BruceK]

check by weight at weigh bridge as per above. If you are significantly out then worry about water. If the decks arent rotten then probably cut holes in buoyancy tanks to fit an inspection hatch and clear out all foam. Replace with plastic soda bottles or similar. Inspection Hatches | Boat Hatches | Force 4 Chandlery

There should be a bung between skins for drainage but if there isnt fit one internally or get a small diaphragm bilge pump, identify a suitable position to core a small hole for the intake tube and pump out after each session or via console switch on demand.

As to where the leak comes from .... ?

However if the buoyancy tanks are above the drainage deck and you pack them tightly with plastic soda bottles (insert with lids off and pack tightly then put lids on) then there is no reason not to drill a small limber hole at the bottom of the tanks for drainage

 

[Sempre Libera]

Good Afternoon, this is my first post on these forums as ive been searching the internet for help with my boat (Bonwitco 449) and cant drum up any specific answers

I recently got the boat along with a 2006 30hp Tohatsu 2 stroke, all went well at the viewing with the engine running up to speed etc but with us being novices we didnt really know what to check to ensure all was sound. looked good and as I expect happens a lot with first boat purchases we went for it and learned about the boat and engine properly with the experience of using it.

First trip out we went fully rigged with fishing gear, anchors, aux engine (Suzuki d5 4stroke on aux bracket) and three adults aboard so a significant amount of weight. got to sea and the engine pretty much failed on us, we limped it in at idling speed and discovered to our cost that the throttle cable was about seized and the throttle control pin was disconnected (plastic clip had disengaged leaving the throttle stuck at idle)

Fearing this would be a common occurrence and hoping to stave off escalating engine repair costs I spoke to a few people with knowledge on the matter and they educated me on proper maintenance and on the spot troubleshooting of common problems IE oiled spark plugs, carb cleaning and how to replace that damned clip when it decides to jump off the throttle control. As a result im comfortable with the engine and am able to keep it going well and up to max revs at sea without issue.

So....to the matter at hand. The bloody boat wont plane. no matter which tilt setting I put the engine at, no matter how we rearrange the weight (we have since been only 2 up) no matter what we do the boat will not get up on the plane even though it is clearly trying to with a frankly enormous wake when underway

I realise it is just a 30hp engine but was lead to believe that bonwitco 449's were an easily planed boat with very little power needed. at the moment i am getting displacement speed with it running at wide open throttle

The boat does feel exceptionally heavy to move about on the trailer when out of the water so I wonder if this may be a water ingress problem, or maybe I just need a bigger engine.

If any current or previous owners of this type of boat could weigh in with their opinion I would very much appreciate it



Cheers.

Ben

Today is your lucky day! I have a Bonwitco 449 with an Evinrude 30hp Etec engine. The boat weighs 250kg plus motor. It WILL plane but only when lightly laden - 2 adults, total 150kg, 45 litres of fuel, 1 Mercury 2.5hp auxiliary plus ropes, safety etc. The addition of 1 child makes levelling off slow or impossible depending on conditions. A heavy chop or headwind will bog it down. My prop peaks at perfect revs when planing and I can then back-off about 500rpm. The default trim is very close in to the transom but once on the plane I can lift it a little to gain a knot or so. Pushing further causes porpoising. On a flat calm I have seen 22 knots. I have tried a whale-tail but to no effect. I have also managed to unstick it by rocking.
So, with family and friends on, I just cruise. I live in the South of France and there is a guy nearby with an outboard dyno. I might try that, in which case I'll let you know the results. On past experience, I doubt if your boat has significant water-logging - the infill is too modern to be absorbent but a small hole at the bottom of the transom will indicate and can be easily filled.
I hope this eases your concerns.